- #1
HHermans
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For a homework assignment I'm supposed to prove that sin(x)^2+cos(x)^2=1, using only the following identities (along with algebraic operations):
sin(-x)=-sin(x)
cos(-x)=cos(x)
cos(x+y)=cos(x)cos(y)-sin(x)sin(y)
sin(x+y)=sin(x)cos(y)+cos(x)sin(y)
I can't figure this out, because as far as I know the identity can only be derived from the Pythagorean Theorem.
Any help would be much appreciated.
sin(-x)=-sin(x)
cos(-x)=cos(x)
cos(x+y)=cos(x)cos(y)-sin(x)sin(y)
sin(x+y)=sin(x)cos(y)+cos(x)sin(y)
I can't figure this out, because as far as I know the identity can only be derived from the Pythagorean Theorem.
Any help would be much appreciated.