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MathsIsFun
2005-09-06 08:06:36

sin θ / (1 + cos θ) = tan ( θ / 2 )
For 30°: (1/2)/(1+√(3)/2) = tan 15°
==> 0.267949 = 0.267949

Yes! (at least for 30°)

John E. Franklin
2005-09-06 04:09:19

A postulate can be derived from the original conversation:

sin θ / (1 + cos θ) = tan ( θ / 2 )

MathsIsFun
2005-08-06 09:53:25

Yes, it is always worth while going back and revising the basics. I do it myself.

skatergirl
2005-08-06 02:52:09

If you are in harder algebra try a bit pre-algebra again

MathsIsFun
2005-07-23 16:38:08

Have a try solving some yourself, here: http://www.mathsisfun.com/worksheets/pr … p;ID=20709

ganesh
2005-07-23 15:59:20

Algebra is using of variables like x,y,z etc to solve mathematical problems.
For example, if you have this problem
#1
When 53 is added to a number, you get 70. What is the number?
The solution would start this way.
Let x be the number.
Therefore, 53 + x = 70
x = 70 - 53 = 17

#2
25 added to the double of a number is 95. What is the number?
Solution:-
Let x be the number.
Therefore, 25 + 2x = 95
2x = 95 - 25 = 70
x = 70/2 = 35

se
2005-07-23 15:51:55

hi i dont now a clue on algrbra can you tell me some stuff

Thushika
2005-07-23 15:50:40

hi i dont now a clue on algrbra can you tell me some stuff

ganesh
2005-07-21 19:17:54

mathsyperson wrote:

My favourite is the one with the square made up of a slightly smaller square and 4 right-angled triangles.

And thats the only one I remember!

MathsIsFun
2005-07-21 18:54:27

* collective bow with mathsyperson shoved forwards *

GurraTedden
2005-07-21 18:20:10

You have both been of great help, and I'm so greatful. To MathIsFun: That was the
solution I knew was there. Mathsyperson: I'm impressed! And regarding the "i want this angle
so bad"; It is written by me, and have been more than true for the last 72 hours. But not any more...
hihi... it's like a burden has been lifted from my shoulders, and the salvator:
"www.mathisfun.com". You guys rock!

mathsyperson
2005-07-21 16:32:14

My favourite is the one with the square made up of a slightly smaller square and 4 right-angled triangles. It's easily the easiest one to understand that I've found so far.

MathsIsFun
2005-07-21 16:22:22

Only because I saw the symmetry - more luck than good management!

BTW, I recently saw a page with 50+ ways of proving Pythagoras, so isn't maths grand?

mathsyperson
2005-07-21 16:12:24

I am extremely annoyed by the easiness of your method and hence the complete pointlessness of mine.
Having said that, well done!

MathsIsFun
2005-07-21 08:31:13

Another way to look at it is:

Solve a triangle that goes straight to the centre of the circle. It is a right-angled triangle, with two sides of 1m and 0.333m. That angle would be tan-1(0.333/1), then double that angle for the result (by symmetry).

I figure it is 36.8°

(Gustav - are you drawing those yourself, or just adding "I want his angle so bad"? If you are, then Good Drafting!)