Question

Question #9a866

Answer 1

`rarrsin120°=sin(180°-60°)=sin60°=sqrt(3)/2`

`rarrcos120°=cos(180°-60°)=-cos60°=-1/2`

`rarrsin240°=sin(180°+60°)=-sin60°=-sqrt(3)/2`

`rarrcos240°=cos(180°+60°)=-cos60°=-1/2`

`rarrsin300°=sin(360°-60°)=-sin60°=-sqrt(3)/2`

`rarrcos300°=cos(360°-60°)=cos60°=1/2`

Note `rarr`sin is not changed into cos and vice versa because we used `180°(90°*2)` and `360°(90°*4)` which are even multiples of `90°` and the sign of the angle is determined by the quadrant to which the angle lies.