Question

求值:(1)sin(-585°)；(2)cos1 935°；(3)tan(-)；(4)cot.

Answer 1

解:(1)sin(-585°)=sin(-360°-225°)=-sin225°=-sin(180°+45°)=sin45°=.

(2)cos1 935°=cos(360°×5+135°)=cos135°=cos(180°-45°)=-cos45°=-.

(3)tan(-)=tan(-4π-)=-tan=-tan(π-)=tan=.

(4)cot=cot(12π+)=cot=1.