cos150°×cos(-570°)×tan(-330°)/cos(-420°)×sin(-690°)
问题描述:
cos150°×cos(-570°)×tan(-330°)/cos(-420°)×sin(-690°)
答
cos150°×cos(-570°)×tan(-330°)/cos(-420°)×sin(-690°)
=-cos30°×cos210°×tan(-30°)/cos60°×sin30°
=-√3/2×(-√3/2)×(-√3/3)/(1/2×1/2)
=3/4×(-√3/3)×4=-√3