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三角函数(1+cos^2)*tan^2-sec^2化成最间单形式是多少>?

题目详情
三角函数
(1+cos^2)*tan^2-sec^2化成最间单形式是多少>?
▼优质解答
答案和解析
(1+cos^2)*tan^2 - sec^2
=(1+cos^2)*(sin^2/cos^2 )- 1/cos^2
=(sin^2/cos^2) + sin^2 - 1/cos^2
=[(sin^2-1)/cos^2] + sin^2
=[-(1-sin^2)/cos^2] + sin^2
=(-cos^2/cos^2) + sin^2
=-1 + sin^2
=-(1-sin^2)
=-cos^2