If #sina + sin^2a = 1,# then what will be# cos^2a + cos^4a #?
2 Answers
Dec 14, 2016
Explanation:
Our starting goal is to turn all terms into cosine. Use the identity
#sina + 1 - cos^2a = 1#
#sina - cos^2a = 0#
#sina = cos^2a#
Square both sides to get rid of the sine.
#(sina)^2 = (cos^2a)^2#
#sin^2a = cos^4a#
Reuse
#1 - cos^2a = cos^4a#
#1 = cos^4a + cos^2a#
Hopefully this helps!
Dec 14, 2016
Given