#1**+5 **

25sinxcosx-5sinx+20cosx= 4

Maybe someone else can solve this one by some algebraic means......but here's a graphical solution.........https://www.desmos.com/calculator/bdgkyrfxh1

It looks like the "x's" that make this true are at 78.5°, 233.1° and 306.9° on the interval [0, 360]

CPhill Mar 3, 2015