Question

How do you solve and find the value of `cos^-1 (1/2)`?

Answer 1

`cos^-1 (1/2) = pi/3 =60^0`

Explanation:

Let `cos^-1 (1/2) =x :. cos x =1/2 ; cos (pi/3) = 1/2 ; cos (2pi-pi/3)=cos ((5pi)/3)=1/2 :. x= pi/3 and x = (5pi)/3`

The range of `cos^-1` is `[0. pi] ; x =(5pi)/3` is out of range. `:. cos^-1 (1/2) = pi/3 =60^0` [Ans]