1.若tana=根号2,求(1)(sina+cosa)/(cosa-sina)的值 (2)2sin^2a-sinacosa+cos^2a的值 2.化简(sin^2atana+cos^2a/tana+2sinacosa)sinacosa

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1.若tana=根号2,求(1)(sina+cosa)/(cosa-sina)的值 (2)2sin^2a-sinacosa+cos^2a的值 2.化简(sin^2atana+cos^2a/tana+2sinacosa)sinacosa
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1.若tana=根号2,求(1)(sina+cosa)/(cosa-sina)的值 (2)2sin^2a-sinacosa+cos^2a的值 2.化简(sin^2atana+cos^2a/tana+2sinacosa)sinacosa
1.若tana=根号2,求(1)(sina+cosa)/(cosa-sina)的值 (2)2sin^2a-sinacosa+cos^2a的值
2.化简(sin^2atana+cos^2a/tana+2sinacosa)sinacosa

1.若tana=根号2,求(1)(sina+cosa)/(cosa-sina)的值 (2)2sin^2a-sinacosa+cos^2a的值 2.化简(sin^2atana+cos^2a/tana+2sinacosa)sinacosa
1)
(sina+cosa)/(cosa-sina)= (tana-1)/(1-tana)
(同时除以cosa)
=1/-1=-1
2)2sin^2a-sinacosa+cos^2a
=(2sin^2a-sinacosa+cos^2a)/(sin^2a+cos^2a)
同时除以cos^2a
=(2tan^2a-tana+1)/(tan^2a+1)
=(8-2+1)/5
=7/5
3)
(sin^2atana+cos^2a/tana+2sinacosa)sinacosa
= (sin^3a/cosa +cos^3a/sina +2sinacosa)sinacosa
=(sin^4a+cos^4a+2sin^acos^2a)
=(sin^2a+cos^2a)^2
=1