用公式求下列各角的三个函数值 (1)(-17π)/3 (2)(21π)/4 (3)(-23π)/6 (4)1500°
问题描述：
用公式求下列各角的三个函数值 (1)(-17π)/3 (2)(21π)/4 (3)(-23π)/6 (4)1500°
答
(1)sin(-17/3π)=sin(-17/3π+6π)=sin(π/3)=√3/2cos(-17/3π)=cos(π/3)=1/2tan(-17/3π)=tan(π/3)=√3(2)sin(21/4π)=sin(21/4π-4π)=sin(5/4π)=sin(π+π/4)=-sinπ/4=-2√2cos(21/4π)=cos(π+π/4)=-cosπ...