Question

If `sinx=1/4` and `tanx` is positive, find `cosx`?

Answer 1

`cosx=sqrt15/4`

Explanation:

As `sinx` and `tanx` both are positive, `x` lies in Quadrant 1 and `cosx=sinx/tanx` too is positive.

Hence, `cosx=sqrt(1-sin^2x)=sqrt(1-(1/4)^2)=-sqrt(1-1/16)=-sqrt(15/16)=sqrt15/4`