作业帮cos150°×cos(-570°)×tan(-330°)/cos(-420°)×sin(-690°)
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cos150°×cos(-570°)×tan(-330°)/cos(-420°)×sin(-690°)
cos150°×cos(-570°)×tan(-330°)/cos(-420°)×sin(-690°)
cos150°×cos(-570°)×tan(-330°)/cos(-420°)×sin(-690°)
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