已知角α终边上一点P(-4,3),求cos(π2+α)−sin(−π−α)cos(11π2−α)+sin(9π2+α)的值.
问题描述:
已知角α终边上一点P(-4,3),求
的值. cos(
+α)−sin(−π−α)π 2 cos(
−α)+sin(11π 2
+α)9π 2
答
∵角α终边上一点P(-4,3),
∴tanα=
=-y x
,3 4
则原式=
=−sinα−sinα −sinα+cosα
=−2tanα −tanα+1
=−2×(−
)3 4
+13 4
.6 7