1991 AHSME Problems/Problem 21

For all real numbers $x$ except $x=0$ and $x=1$ the function $f(x)$ is defined by $f(x/(1-x))=1/x$. Suppose $0\leq t\leq \pi/2$. What is the value of $f(\sec^2t)$? The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. AMC logo.png

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