How do you evaluate $cos ^-1 (1/2)$ ?

Question

5409 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-05-23T09:34:33

$cos^(-1)(1/2)=2npi+-pi/3$ where $n$ is an integer.

We know that $cos(pi/3)=1/2$ , however as

$cos(-theta)=costheta$ , we also have $cos(-pi/3)=1/2$

Further function cosine has a periodicity of $2pi$

hence $cos^(-1)(1/2)=2npi+-pi/3$ where $n$ is an integer.

How do you evaluate cos ^-1 (1/2)cos ^-1 (1/2)?