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.
triple angle formula can be used to find the exact value of tan 36 and tan 72.(Happy)
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