[3sin^2 (a/2)-2sin(a/2)cos(a/2)+cos^2 (a/2)]/[tana+1/tana]_数学解答

[3sin^2 (a/2)-2sin(a/2)cos(a/2)+cos^2 (a/2)]/[tana+1/tana]

人气：448 ℃　时间：2020-09-19 14:58:53

解答

分子=3(1-cosa)/2-sina+(1+cosa)/2
=2-cosa-sina
分母=sina/cosa+cosa/sina
=(sin²a+cos²a)/sinacosa
=1/sinacosa
所以原式=sinacosa(2-cosa-sina)
=2sinacosa-sin²acosa-sinacos²a