原式=sin(-α-π)•cos(α-π2)
=sin α•sin α=sin2 α.
故答案为:sin2 α.
信用卡的基本功能主要表现在()、()、()三种功能。
The coach explained the regulations at length to make sure that none of his players world become violators.
A.at last
B.at large
C.in detail
D.in short