化简求值(1)sin(-1320°)•cos1110°+cos(-1020°)sin750°(2)sin(2π-α)•cos(-π+α)sin(3π-α)•cos(π+α).-数学

题目简介

化简求值(1)sin(-1320°)•cos1110°+cos(-1020°)sin750°(2)sin(2π-α)•cos(-π+α)sin(3π-α)•cos(π+α).-数学

题目详情

化简求值
(1)sin(-1320°)•cos1110°+cos(-1020°)sin750°
(2)
sin(2π-α)•cos(-π+α)
sin(3π-α)•cos(π+α)
题型:解答题难度:中档来源:不详

答案

(1)原式=sin(-4×360°+120°)•cos(3×360°+30°)+cos(-3×360°+60°)sin(2×360°+30°)
=
3
2
×
3
2
+class="stub"1
2
×class="stub"1
2
=1;
(2)原式=class="stub"sinαcosα
-sinαcosα
=-1.

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