来自刘伯兴的问题
【高一数学必修四的一道函数求证题目、tan^2a-sin^2a=tan^2a*sin^2a】
高一数学必修四的一道函数求证题目、
tan^2a-sin^2a=tan^2a*sin^2a
1回答
2020-05-07 00:20
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何洲平
tan^2a-sin^2a
=sin^2a/cos^2a-sin^2a
=sin^2a(1/cos^2a-1)
=sin^2a*[(1-cos^2a)/cos^2a]
=sin^2a*[sin^2a/cos^2a]
=sin^2a*tan^2a,
故：tan^2asin^2a=tan^2a-sin^2a.
2020-05-07 00:22:56