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

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Answer 1 · 2016-11-26T05:59:08

$arccos(-1/2)=(2pi)/3$

$arccosx$ is an angle whose cosine ratio is $-1/2$ .

Now as $cos(pi/3)=1/2$ and $cos (pi-A)=-cosA$

$cos(pi-pi/3)$ i.e. $cos((2pi)/3)=-coe(pi/3)=-1/2$

As $cos((2pi)/3)=-1/2$ , we have

$arccos(-1/2)=(2pi)/3$

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