tan^2α=2tan^2 β+1则 cos2α+sin^2β等于?

tan^2α=2tan^2 β+1则 cos2α+sin^2β等于?

tan^2α=2tan^2 β+1
1+tan²α=2(1+tan²β)
sec²α=2sec²β
1/cos²α=2/cos²β
2cos²α=cos²β
cos²α=(1-sin²β)/2
(1+cos2α)/2=(1-sin²β)/2
1+cos2α=1-sin²β
cos2α+sin²β=1-1
cos2α+sin²β=0