How do you simplify sec(tan^(-1)(x)) ?

1 Answer
Aug 8, 2018

sec(tan^(-1)(x))=sqrt(x^2+1)

Explanation:

sec(tan^(-1)(x))

let y=tan^(-1)(x)

x=tan(y)

x=sin(y)/cos(y)

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

x^2+1=(cancel(cos(y)^2+sin(y)^2)^(=1))/cos(y)^2

x^2+1=sec(y)^2

sqrt(x^2+1)=sec(y)=sec(tan^(-1)(x))

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