问题
填空题
已知tanx=2,则
|
答案
∵tanx=2,
则
=3sin2x+2cos2x cos2x-3sin2x 6sinxcosx+2(cos2x-sin2x) cos2x-sin2x-6sinxcosx
=
+2×6sinxcosx sin2x+cos2x cos2x-sin2x cos2x+sin2x cos2x-sin2x-6sinxcosx sin2x+cos2x
=
+2×6tanx 1+tan2x 1-tan2x 1+tan2x 1-tan2x-6tanx 1+tan2x
=-7 15