How do you evaluate $cos(cos^-1(1/2))$ without a calculator?

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Answer 1 · 2017-02-19T20:56:20

$1/2$

$cos " and " cos^-1" are the inverse of each other"$

$"and "f(f^-1(x))=xlarr"in general"$

$rArrcos(cos^-1(1/2))=1/2$

How do you evaluate cos(cos^-1(1/2))cos(cos^-1(1/2)) without a calculator?