[tan(45+a)/1-tan^2(45+a)]*[sinacosa/cos^2a-sin^2a]

dreamtime2022-10-04 11:39:541条回答

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keyi123 共回答了19个问题 | 采纳率94.7%
[tan(45+a)/1--tan^2(45+a)]*[sinacosa/cos^2a--sin^2a]
=1/2[tan(45+a)]*[1/2(sin2a/cos2a)]
=1/4[tan2(45+a)*tan2a)]
=1/4tan(90+2a)*tan2a
=1/4cot2a*tan2a
=1/4.
1年前

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