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