## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$f(x)=\sqrt x$ and $g(x)=1-x^2$
We wish to find two functions $f$ and $g$ such that: $H(x)=(f \circ g)(x) =\sqrt {1-x^2}$ Let us consider: $f(x)=\sqrt x$ and $g(x)=1-x^2$ Then we have the composite function: $H(x)=(f \circ g)(x) =f[g(x)]=f(1-x^2)=\sqrt {1-x^2}$