Question

How do i solve cos (-60(degrees)) to exact values?

Answer 1

1/2

Explanation:

`cos(-60^0)`.
first convert `60^0` in radians just for the sake of convenience of problem solving in trigonometry. since `pi` radian =`180^0` `rArr 60^0=(pi/3) radians`
now, since `cos(-theta)=costheta` ,
so, `cos(-pi/3)=cos(pi/3)=1/2` (a standard value and should be memorised)