How to simplify sin(sec^(-1)(x)) ?

1 Answer
Aug 2, 2018

sin(sec^(-1)(x))=sqrt(x^2-1)/x

Explanation:

sin(sec^(-1)(x))=sin(cos^(-1)(1/x))

Let y=cos^(-1)(1/x)

x=1/cos(y)

1/x^2=cos(y)^2=1-sin(y)^2

1/x^2-1=-sin(y)^2

(x^2-1)/x^2=sin(y)^2

sqrt(x^2-1)/x=sin(y)=sin(sec^(-1)(x))

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