Hello. This is a problem from a book I'm studying on, I can't understand the solution.

"Find each segment formed by an inscribed equilateral triangle if the radius of the circle is 8"

Solution

R=8. Since , the area of is .

Also, area of circle O = .

Hence area of segment BDC =

These are my questions:

1.- Why is ?

2.And why is the area of equal to ? I know the area of a triangle is equal to , how do you get the height?

Thanks.