tan²α=2tan²θ+1求证cos2α+sin²θ=0
问题描述:
tan²α=2tan²θ+1求证cos2α+sin²θ=0
答
∵tan²α=2tan²θ+1
∴tan²α=-1
∴cos2α+sin²θ
=cos²a-sin²+sin²
=cos²a
=1/[sec²a]
=1/[1+tan²a]
=1/0
=∞