#1**+1 **

Drawing an altitude from the apex to the base forms two 30-60-90 right triangles

In one of the triangles, the base = 10 and this is the side opposite the 60° angle

The height of this triangle [ and of the larger triangle] will be opposite the 30° angle and wil be 10/√3 units long

So....the area of the biggger triangle = (1/2)base * height =

(1/2) 20 * 10/√3 = 100/√3 sq units

Here's a pic

CPhill
Jul 7, 2017