已知a为锐角,且sina=4/5.(1)求sin²a+sin2a/cos²a+cosa (2)求tan(a-5π/4)的值

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已知a为锐角,且sina=4/5.(1)求sin²a+sin2a/cos²a+cosa (2)求tan(a-5π/4)的值
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已知a为锐角,且sina=4/5.(1)求sin²a+sin2a/cos²a+cosa (2)求tan(a-5π/4)的值
已知a为锐角,且sina=4/5.(1)求sin²a+sin2a/cos²a+cosa (2)求tan(a-5π/4)的值

已知a为锐角,且sina=4/5.(1)求sin²a+sin2a/cos²a+cosa (2)求tan(a-5π/4)的值
a为锐角,sina=4/5所以cosa=3/5 ,tana=4/3
(1)
sin²a+sin2a/cos²a+cosa
=sin²a+2sina·cosa/cos²a+cosa
=sin²a+2sina/cosa+cosa
=(4/5)^+2*4/3+3/5
=293/75
(2)
tan(a-5π/4)
=tan(a-π/4)
=-1/tana
=-3/4