Last edited by mr fantastic; Sep 24th 2011 at 03:52 AM.
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The Problem is very easy.
no I know this is easy
Okay sorry I read
hahah very quickly I dont understad where you get worth of tan^2(36) tan^(72) can you explain
He multiplied! .
Now, if you are asking how sbhatnagar determined that , that's a really good question! Come on, sbhatnagar, let us in on the secret.
Last edited by HallsofIvy; Sep 24th 2011 at 11:42 AM.
triple angle formula can be used to find the exact value of tan 36 and tan 72.
Originally Posted by HallsofIvy He multiplied! .
Now, if you are asking how sbhatnagar determined that , that's a really good question! Come on, sbhatnagar, let us in on the secret. To calculate tan(36 degrees), I'd consider a regular pentagon ....
To find sin(72):
Let x = 18
So now using quadratic formula,
Now use sin^(2)x+cos^(2)x=1 to find cos(x)
Now you have,
If then and
The value of sin(36 degrees) can be found by using the formula of sin(2x).
ha ha I searched a lot of similar crazy expressions. It seems difficult to learn all of them. Exact trigonometric constants - Wikipedia, the free encyclopedia Trigonometry Angles -- from Wolfram MathWorld
Last edited by BookEnquiry; Oct 11th 2011 at 10:48 PM.
Last edited by BookEnquiry; Oct 11th 2011 at 08:04 AM.
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