# Trigonometric problem 3

Prove that $$[ \cos^{-1} \circ \cos ] (x) = [\cos \circ \cos^{-1}] (x)$$ find the value of $$x$$.

Note by A Brilliant Member
2 years, 5 months ago

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$$cos(cos^{-1}x)= x$$ for $$x\in[-1,1]$$

& $$cos^{-1}(cosx)=x$$ for $$x\in[0,\pi]$$

So $$cos(cos^{-1}x)=cos^{-1}(cosx)$$ only $$x\in[0,1]$$

- 2 years, 5 months ago