Hello! remember you have to write complete questions in order to get good and exact answers. Here you haven't provided any figure, so I'll choose the figure below in order to illustrate this problem. A composite polygon is a polygon that can be divided into two or more basic shapes. So here we have a composite polygon formed by a triangle and a rectangle. So:
You can get this by creating right triangles with the adjacent side as 20 and using the angles given. You can then find the opposite sides using tangents and then simply add them together. <span />