Question

高一数学、三角函数 计算

不太明白...亲给下过程
求值sin(-1320°）*cos1110°+cos（-1020°）sin750°+tan（-405°）

求值sin25π/6+cos25π/3+tan25π/4+sin7π/3*cos13π/6-cos5π/3

Answer 1

sin(-1320°）*cos1110°+cos（-1020°）sin750°+tan（-405°）
=sin120°cos30°+cos60°sin30°-tan45°
=sin60°cos30°+cos60°sin30°-tan45°
=3/4+1/4-1
=0

sin25π/6+cos25π/3+tan25π/4+sin7π/3*cos13π/6-cos5π/3
=sinπ/6+cosπ/3+tanπ/4+sinπ/3cosπ/6-cosπ/3
=1/2+1/2+1+√3/2(1/2)-1/2
=3/2+√3/4

Answer 2

sin60°*√3/2+cos(180°+120°)*1/2-1=3/4-cos120°-1=3/4-1/4-1=-1/2