已知(1+sin a)/cos a=-1/2,则cosa/(sina-1)得值是?同上
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已知(1+sin a)/cos a=-1/2,则cosa/(sina-1)得值是?同上
已知(1+sin a)/cos a=-1/2,则cosa/(sina-1)得值是?
同上
已知(1+sin a)/cos a=-1/2,则cosa/(sina-1)得值是?同上
(1+sin a)/cos a ÷ cosa/(sina-1)
= (1+sin a)(sina-1) / (cosa)^2
= [ (sina)^2 - 1 ] / (cosa)^2
= -(cosa)^2 / (cosa)^2
= -1
所以:
cosa/(sina-1)
= -(1+sin a)/cos a
= 1/2