Write the trigonometric expression as an al gebraic expressi

Write the trigonometric expression as an al gebraic expression in u

Solution

cos(tan^-1u)

Let tan^-1u=x

tan x=u/1

oppposite=u, adjacent =1

hypotenuse=sqrt(1+u²)

cos x=adjacent/hypotenuse =1/sqrt(1+u²)

So cos(tan^-1u)=1/sqrt(1+u²)