An equilateral triangle has an area of 9 radical 3 square inches. how many inches is the perimeter?
The altitude divides the triangle into two 30-60-90 triangles. The short leg is ½ the base, or b/2. So, the altitude is b√3/2. Area of full triangle is half base times height so:
A=(b/2)*(b√3/2)=(b²√3)/4 = 9√3
That means b²/4 = 9
Perimeter is 3b =3*6 = 18 inches