Last edited by mr fantastic; September 24th 2011 at 02:52 AM. Reason: Re-titled.
Follow Math Help Forum on Facebook and Google+
The Problem is very easy.
no I know this is easy but
Okay sorry I read also, Therefore
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; September 24th 2011 at 10:42 AM.
yes
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, Therefore
If then and Therefore 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; October 11th 2011 at 09:48 PM.
Last edited by BookEnquiry; October 11th 2011 at 07:04 AM.
View Tag Cloud