- #1
Beer w/Straw
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The problem is... What to put as my answer :P arcsin(Sin(7Pi/5))
http://mathworld.wolfram.com/TrigonometryAnglesPi5.html
The solution is -2Pi/5
The problem I'm having is this appears to me as a trick question. Would it be acceptable to say
sin(7pi/5) = -(sqrt(5/8+sqrt(5)/8)) make a note of an identity. Then simply say arcsin(-(sqrt(5/8+sqrt(5)/8))) =-2Pi/5?
Assuming this is correct, would not all the work I just cut out be acceptable because I'm not trying to prove the identity over again?
Comments suggestions would be appreciated.
Thanks.
PS: Sorry for lack of tex.
http://mathworld.wolfram.com/TrigonometryAnglesPi5.html
The solution is -2Pi/5
The problem I'm having is this appears to me as a trick question. Would it be acceptable to say
sin(7pi/5) = -(sqrt(5/8+sqrt(5)/8)) make a note of an identity. Then simply say arcsin(-(sqrt(5/8+sqrt(5)/8))) =-2Pi/5?
Assuming this is correct, would not all the work I just cut out be acceptable because I'm not trying to prove the identity over again?
Comments suggestions would be appreciated.
Thanks.
PS: Sorry for lack of tex.