Leibniz’s Linear differential equation Problems and Solutions

A German mathematician Gottfried Wilhelm Leibniz (or Leibnitz) introduced a solution for the linear differential equation of first order and first degree. The following the list of questions on Leibnitz’s linear differential equation with solutions to learn how to find the solution for the first order linear differential equation.

Solve $\cos^2{x}\dfrac{dy}{dx}$ $+$ $y$ $\,=\,$ $\tan{x}$