SOLUTION: Hello, this is the problem I'm stuck on. Given that the exact value of sin pi/10=(-1+sqrt 5)/4, for each question calculate the exact value of the given expression. YOU MAY LEAV

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Question 1093349: Hello, this is the problem I'm stuck on.
Given that the exact value of sin pi/10=(-1+sqrt 5)/4, for each question calculate the exact value of the given expression. YOU MAY LEAVE NESTED RADICALS IN YOUR ANSWER, BUT RATIONALIZE ANY DENOMINATORS.
1. sin pi/20.
I appreciate any help and thanks in advance!

Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
Look at "Half angle formulas" on Wikipedia.

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