Question

化简：sin(-1320度）cos1110度+cos(-1020度）sin750度+tan390度

Answer 1

sin（-1320°）cos1110°+cos（-1020°）sin750°+tan390°
= sin120°cos30°+cos60°sin30°+tan30°
= sin60°cos30°+cos60°sin30°+tan30°
= √3/2×√3/2+1/2×1/2+√3/3
= 3/4+1/4+√3/3
= 1+√3/3

希望你能采纳，不懂可追问。谢谢。

Answer 2

sin-1320°
=sin(1440°-1320°)
=sin120°
=√3/2
cos1110°+cos-1020°
=cos(1110°-1080°)+cos(1080°-1020°)
=cos30°+cos60°
=√3/2+1/2
sin750°+tan390°
=sin(750°-720°)+tan(390°-360°)
=sin30°+tan30°
=1/2+√3/3