这题我来帮你解一波!
原式=tan(-150°)cos(-570°)cos(-1140°)tan(-240°)/sin(-690°)
= tan(-180°+30°)cos(-720°+150°)cos(-1260°+120°)tan(-360°+120°)/sin(-720°+30°)
= tan30°×cos150°×(-cos120°)×tan120°/sin30°
= √3/3 × (-√3/2) × 1/2 × (-√3) ÷ 1/2
= √3/2
要是还有不懂的欢迎继续问哈~
原式=tan(-150°)cos(-570°)cos(-1140°)tan(-240°)/sin(-690°)
= tan(-180°+30°)cos(-720°+150°)cos(-1260°+120°)tan(-360°+120°)/sin(-720°+30°)
= tan30°×cos150°×(-cos120°)×tan120°/sin30°
= √3/3 × (-√3/2) × 1/2 × (-√3) ÷ 1/2
= √3/2
要是还有不懂的欢迎继续问哈~