The circle above has center O and area 9*pi. Triangle ABC is equilateral. Find its area.

Guest Jan 2, 2020

#1**+1 **

This is what I did:

I noticed that segment AO and OD are radii, and since radii are all congruent, center O must also be the midpoint of AD.

I calculated OD because it was a radii.

Then I multiplied the value of OD by 2 to get AD. We know know the height of triangle ABC.

Since ABC Is equilateral, that means angles C and B are 60 degrees.

We find that triangles ACD and ABD are 30-60-90 triangles.

Since we know the height of triangle ABC and we know that triangles ACD and ABD are 30-60-90, can you find the area?

Hint: try using the properties of a 30-60-90 triangle.

CalculatorUser Jan 2, 2020