求下列三角函数值 （1)sin7p／3 (2)cos17p／4 (3)tan(－23p／6) (4)sin(－765°)

Question

如题所述

Answer 1

（1)sin7p／3
=sin(2π+π/3）=sinπ/3=根号3/2

(2)cos17p／4
=cos(4π+π/4)=cosπ/4=根号2/2

(3)tan(－23p／6)
=tan(-4π+π/6)=tanπ/6=根号3/3

(4)sin(－765°)
=sin（-720°-45°）=-sin45°=-根号2/2

Answer 2

用诱导公式
sin(7p/3)=sin(p/3)=√3/2
cos(17p/4)=cos(p/4)=√2/2
tan(-23p/6)=tan(p/6)=√3/3
sin(-765°)=-sin45°=-√2/2