CPM Homework Help : CCG Problem 8-56

Find the area of an equilateral triangle with side length $20$ mm. Draw a diagram and show all work.

Hint:

An equilateral triangle with sides length 20.0 millimeters. All three angles are 60 degrees. A dashed line is drawn from the upper vertex to the base forming a right angle.

Answer:

$A=100\sqrt{3}\approx 173.2 \text{ mm}^2$