Dx + (x cot y+ sin y)dy=0 ,solve the de

Multiply both sides by :

The ODE is now exact, since

so there exists a solution of the form . This solution satisfies

Integrating both sides of the first PDE wrt gives

and differentiating wrt gives

So the ODE has solution

which can be rewritten and simplified as

step-by-step explanation:

180°

step-by-step explanation:

sum of equilateral triangle=180°

< n=60°

< m=120°°[angle supplementary of equilateral angle]

< m+< r+< x=360°(sum of exterior angle of triangle)