Math Is Fun Forum

jadewest

Member

Registered: 2021-02-20

Posts: 44

The Cartesian Coordinate System and the Distance Formula

Hello,
I am having trouble with two exercises related to this subject.

The first one states:

4.

What shape do these four points make? (Draw from one to the next in the order given,
and then draw from the last back to the first).

(0,-1), (0,3), (1,1), (-1,1)

A. A square
B. Two acute angles that meet at the acute angles
C. A triangle
D. Two right triangles that meet at the right angles
E. A rhombus
F. Two obtuse triangles that meet at the hypotenuse

My problem is that the figure that comes out is a rhombus, which is the same figure for exercise 3. I am getting confused in whether I'm right or not.

The second exercise is:

Find the distance between the two points:
14. (9, 0) and (-3, -8)

A. 4
B. √(61)
C. √(290)
D. 4[√(13)]
E. 5[√(17)]
F. 3[√(180)]

This is what I've done:
distance = sqrt (-3-9)^2 + (-8-0)^2
d = sqrt (-12)^2 + (-8)^2
d = sqrt 144+64
d = sqrt 208

The problem is that my result is not an alternative.

Thank you in advance!!!

gustavowoltmann

Member

Registered: 2021-02-23

Posts: 1

Re: The Cartesian Coordinate System and the Distance Formula

Oh its very interesting article, Form starting i love math subject. If you have need so i can give good information about math subjects. Gustavo Woltmann

Bob

Administrator

Registered: 2010-06-20

Posts: 10,803

Re: The Cartesian Coordinate System and the Distance Formula

hi jadewest

Q4.  If you just plot these four points, then they do seem to make a rhombus, but the questions says join them in order.  The lines joining (0,-1) to (0,3) and (1,1) to ( -1,1) cross over so rhombus is not the answer.

Q14.  Your working is correct but there is one more step you can make.

√ 208 = √ (16x13) = √ 16 x √ 13.

So you have found an answer they is one of the ones given.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

jadewest

Member

Registered: 2021-02-20

Posts: 44

Re: The Cartesian Coordinate System and the Distance Formula

Hi Bob,
So the right answer for Q14 would be the 4 * sqrt 13, or alternative D.

I'm sorry, but I'm still confused in Q4. Even if I put them in the order given in the exercise, the figure that comes out is a rhombus. I'm not sure what exactly I'm doing wrong.

jadewest

Member

Registered: 2021-02-20

Posts: 44

Re: The Cartesian Coordinate System and the Distance Formula

I think I finally got Q4!!! In the exercise it says this: (Draw from one to the next in the order given,
and then draw from the last back to the first). When I connect the points in the given order I notice that I create two right triangles that meet at the right angles. So, the right alternative is D.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,803

Re: The Cartesian Coordinate System and the Distance Formula

hi jadewest

Your answers are the same as mine now.  Good!

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

jadewest

Member

Registered: 2021-02-20

Posts: 44

Re: The Cartesian Coordinate System and the Distance Formula

Thank you for your help, I appreciate it!!