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Pythagoras Theorem
Pythagoras Theorem: In a right angled triangle, the square of the hypotenuse is equal to the sum of the squares of the two sides.
A right angled Triangle ABC, right angled at B.
gives
{AC}^2 = {AB}^2 + {BC}^2
gives
3^2 square units+ 4^2 square units = 5^2 square units
gives
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Trigonometric Ratios Formulas
Trigonometric ratios can be calculated by taking the ratio of any two sides of the right-angled triangle. We can evaluate the third side using the Pythagoras theorem, given the measure of the other two sides. We can use the abbreviated form of trigonometric ratios to compare the length of any two sides with the angle in the base. The angle θ is an acute angle (θ < 90º) and in general is measured with reference to the positive x-axis, in the anticlockwise direction. The basic trigonometric ratios formulas are given below,
sin\theta = Perpendicular / Hypotenuse
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cos\theta = Base / Hypotenuse
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tan\theta = Perpendicular / Base
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sec\theta = Hypotenuse / Base
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cosec\theta = Hypotenuse / Perpendicular
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cot\theta = Base / Perpendicular
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.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Trigonometric Ratios of Complementary Angles Identities
The complementary angles are a pair of two angles such that their sum is equal to 90°. The complement of an angle θ is (90° - θ). The trigonometric ratios of complementary angles are:
sin (90°- \theta) = cos \theta
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cos (90°- \theta) = sin \theta
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cosec (90°- \theta) = sec \theta
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sec (90°- \theta) = cosec \theta
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tan (90°- \theta) = cot \theta
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cot (90°- \theta) = tan \theta
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.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Pythagorean Trigonometric Ratios Identities
These can be derived: Pythagorean trigonometric ratios identities:
{sin}^2\theta + {cos}^2\theta = 1
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1 + {tan}^2\theta = {sec}^2\theta
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.1 + {cot}^2\theta = {cosec}^2\theta
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.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Sum, Difference, Product Trigonometric Ratios Identities
The sum, difference, and product trigonometric ratios identities include the formulas of sin(A+B), sin(A-B), cos(A+B), cos(A-B), etc.
sin (A + B) = sin A cos B + cos A sin B
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sin (A - B) = sin A cos B - cos A sin B
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cos (A + B) = cos A cos B - sin A sin B
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cos (A - B) = cos A cos B + sin A sin B
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tan (A + B) = (tan A + tan B)/ (1 - tan A tan B)
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tan (A - B) = (tan A - tan B)/ (1 + tan A tan B)
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cot (A + B) = (cot A cot B - 1)/(cot B - cot A)
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cot (A - B) = (cot A cot B + 1)/(cot B - cot A)
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2 sin A⋅cos B = sin(A + B) + sin(A - B)
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2 cos A⋅cos B = cos(A + B) + cos(A - B)
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2 sin A⋅sin B = cos(A - B) - cos(A + B)
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.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Note:
So, the new set of formulas for trigonometric ratios is:
sin \theta = 1/cosec\theta
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cos \theta = 1/sec\theta
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tan \theta = 1/cot \theta
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cosec \theta = 1/sin \theta
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sec \theta = 1/cos \theta
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cot \theta = 1/tan \theta
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.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Double Angle Identities
Double angle identities for reference:
sin 2\theta = 2 sin\theta cos\theta
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cos 2\theta = {cos}^2\theta - {sin}^2\theta
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tan 2\theta = (2 tan\theta)/(1 - {tan}^2\theta)
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sec 2\theta = \dfrac{{sec}^{2}\theta}{(2-{sec}^2\theta)}
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cosec 2\theta = \dfrac{(sec \theta \cdot cosec \theta)}{2}
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cot 2\theta = \dfrac{(cot \theta - tan \theta)}{2}
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.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Triple Angle Trigonometric Ratios Identities
sin 3\theta = 3sin \theta - 4{sin}^3\theta
gives
cos 3\theta = 4{cos}^3\theta - 3cos\theta
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tan 3\theta = (3tan\theta - {tan}^3\theta)/(1 - 3{tan}^2\theta)
gives
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Distance between any Two Points in a Cartesian Plane
PQ = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}
gives
or
PQ = \sqrt{(x_1 - x_2)^2 + (y_1 - y_2)^2}
gives
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Coordinate Geometry
OP = \sqrt{x^2 + y^2}
is
.\left(\dfrac{m_1x_1 + m_2x_2}{m_1 + m_2}, \dfrac{m_1y_1+ m_2y_2}{m_1 + m_2}\right)
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and
\left(\dfrac{m_1x_1 - m_2x_2}{m_1 - m_2}, \dfrac{m_1y_1- m_2y_2}{m_1 - m_2}\right)
gives
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Coordinates of the mid-point
\left(\dfrac{x_1 + x_2}{2}, \dfrac{y_1 + y_2}{2}\right).
gives
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Slope
One way of finding Slope
We can find the slope of the line using different methods. The first method to find the value of the slope is by using the equation is given as,
m = \dfrac{(y_2 - y_1)}{(x_2 - x_1)}
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where m is the slope of the line.
y = mx + b
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.tan\theta = |\dfrac{m_1 - m_2}{1 + m_1m_2}|
gives
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Slope
tan\theta = \dfrac{y_2 - y_1}{x_2 - x_1}
gives
m = tan\theta
gives
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Equation of Straight Line : Two Point Form
\dfrac{y - y_1}{y_2 - y_1} = \dfrac{x - x_1}{x_2 - x_1}
gives
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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The centroid of a Triangle
The centroid of a triangle is the point of intersection of medians of a triangle. (Median is a line joining the vertex of a triangle to the mid-point of the opposite side.). The centroid of a triangle having its vertices
A(x_1,y_1), B(x_2, y_2), C(x_3, y_3)
gives
is obtained from the following formula:
(x, y) = \left(\dfrac{x_1 + x_2 + x_3}{3}, \dfrac{y_1 + y_2 + y_3}{3}\right)
gives
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Distance Formulas - I
d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}
is
.d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2 + (z_2 - z_2)^2}
is
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Distance Formula - II
Distance From a Point To a Line in 2D
The distance formula to calculate the distance from a point to a line is the length of the perpendicular line segment that is drawn from the point to the line. Let us consider a line L in a two-dimensional plane with the equation ax + by + c =0 and consider a point
.Then the distance (d) from P to L is,
d = \dfrac{|ax_1 + by_1 + c|}{\sqrt{x^2 + y^2}}
gives
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Area of a Triangle
\left\{\dfrac[{1}{2}x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2)]\right\}
gives
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Collinearity of three points
x_1(y_2 - y_3) + y_2(y_3 - y_1) + x_3(y_1 - y_2) = 0
gives
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Quadrilateral
A = (1/2) ⋅ {(x_1y_2 + x_2y_3 + x_3y_4 + x_4y_1) - (x_2y_1 + x_3y_2 + x_4y_3 + x_1y_4 )}
gives
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Angle Between Straight Lines
tan \ \theta = \left|\dfrac{m_1 - m_2}{1 + m_1{m_2}}\right|
gives .
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Angle between Straight Lines
tan \ \theta = \left|\dfrac{{a_2}{b_1} - {a_1}{b_2}}{{a_1}{a_2} + {b_1}{b_2}}
gives
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Angle between two straight lines
\theta = {Tan}^{-1} \dfrac{m_1 - m_2}{1 + m_1 \cdot m_2}
gives
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Circle
A circle is a curved plane figure. Every point on the circle is equidistant from a fixed point known as the center of the circle. It is a 2D shape and is measured in terms of radius. The word ‘Circle’ is derived from the Latin word 'circulus' meaning small ring.
What is Circle?
A circle is a two-dimensional figure formed by a set of points that are at a constant or at a fixed distance (radius) from a fixed point (center) on the plane. The fixed point is called the origin or center of the circle and the fixed distance of the points from the origin is called the radius.
Parts of a Circle
There are many parts or components of a circle that we should know to understand its properties. A circle has mainly the following parts:
* Circumference: It is also referred to as the perimeter of a circle and can be defined as the distance around the boundary of the circle.
* Radius of Circle: Radius is the distance from the center of a circle to any point on its boundary. A circle has many radii as it is the distance from the center and touches the boundary of the circle at various points.
* Diameter: A diameter is a straight line passing through the center that connects two points on the boundary of the circle. We should note that there can be multiple diameters in the circle, but they should:
** pass through the center.
** be straight lines.
** touch the boundary of the circle at two distinct points which lie opposite to each other.
* Chord of a Circle: A chord is any line segment touching the circle at two different points on its boundary. The longest chord in a circle is its diameter which passes through the center and divides it into two equal parts.
* Tangent: A tangent is a line that touches the circle at a unique point and lies outside the circle.
* Secant: A line that intersects two points on an arc/circumference of a circle is called the secant.
* Arc of a Circle: An arc of a circle is referred to as a curve, that is a part or portion of its circumference.
* Segment in a Circle: The area enclosed by the chord and the corresponding arc in a circle is called a segment. There are two types of segments - minor segment, and major segment.
* Sector of a Cirlce: The sector of a circle is defined as the area enclosed by two radii and the corresponding arc in a circle. There are two types of sectors - minor sector, and major sector.
Properties of Circle
Here is a list of properties of a circle:
* A circle is a closed 2D shape that is not a polygon. It has one curved face.
* Two circles can be called congruent if they have the same radius.
* Equal chords are always equidistant from the center of the circle.
* The perpendicular bisector of a chord passes through the center of the circle.
* When two circles intersect, the line connecting the intersecting points will be perpendicular to the line connecting their center points.
* Tangents drawn at the endpoints of the diameter are parallel to each other.
Let's see the list of important formulae pertaining to any circle.
Area of a Circle Formula: The area of a circle refers to the amount of space covered by the circle. It totally depends on the length of its radius :
Area = \pi{r^2} square units
gives .
.Circumference of a Circle Formula: The circumference is the total length of the boundary of a circle.
Circumference = 2\pi{r} units
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Arc Length Formula: An arc is a section (part) of the circumference.
Length \ of \ an \ arc = \theta \times r. \ Here, \theta \ is \ in \radians.
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Area of a Sector Formula: If a sector makes an angle θ (measured in radians) at the center, then the area of the sector of a circle =
(\theta \times r^2) \div 2. \ Here, \theta \ is \ in \ radians.
gives
Length of Chord Formula: It can be calculated if the angle made by the chord at the center and the value of radius is known.
Length \ of \ chord = 2 r sin\dfrac{\theta}{2}. \ Here, \ \theta \ is \ in \ radians.
gives
Area of Segment Formula: The segment of a circle is the region formed by the chord and the corresponding arc covered by the segment.
The \ area \ of \ a \ segment = r^2(\theta − sin\theta) \div 2. Here, \theta \ is \ in \ radians.
gives
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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Important Notes on Angles
0^o < \ Acute \ angle < \ {90}^o
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{90}^o < \ Obtuse \ angle < {180}^o
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{180}^o < \ Reflex \ angle < {360}^o
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A \ right \ angle \ is \ equal \ to \ {90}^o
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A \ straight \ angle \ is \ equal \ to {180}^o.
gives
.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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