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Question
Prove that : sin^4ϴ-1/cos^2ϴ = cos^2ϴ-2
if by this you mean
(sin(A)^4 - 1)/cos(A)^2 = cos(A)^2 - 2
((sin(A)^2 - 1)(sin(A)^2 + 1))/(1 - sin(A)^2) = cos(A)^2 - 2
((sin(A)^2 - 1)(sin(A)^2 + 1))/(-sin(A)^2 + 1) = cos(A)^2 - 2
((sin(A)^2 - 1)(sin(A)^2 + 1))/(-(sin(A)^2 - 1) = cos(A)^2 - 2
-sin(A)^2 - 1 = cos(A)^2 - 2
-(1 - cos(A)^2) - 1 = cos(A)^2 - 2
-1 + cos(A)^2 - 1 = cos(A)^2 - 2
cos(A)^2 - 2 = cos(A)^2 - 2
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| Comment | Thank you...my problem was one of sign, I forgot to put the negative in front of the sin squared theta in the beginning and it threw me all off. Thank you so much! | ||
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