(1-sin(a)^6-cos(a)^6)/(1-sin(a)^4-cos(a)^4) (1-sin(a)^6-cos(a)^6)/(1-sin(a)^4-cos(a)^4)
问题描述:
(1-sin(a)^6-cos(a)^6)/(1-sin(a)^4-cos(a)^4)
(1-sin(a)^6-cos(a)^6)/(1-sin(a)^4-cos(a)^4)
答
设x=(sin@)平方,则(cos@)平方=1-x.
原式=[1-x立方-(1-x)立方] / [1-x平方-(1-x)平方]
=(3x-3x平方)/(2x-2x平方)
=3/2 .