perimeter of triangle in circle

[jmckmills]

I need to find the perimeter of an equilateral triangle inside a circle with a radius of 6....can you help me get started?

 

[Deleted member 4993]

I need to find the perimeter of an equilateral triangle inside a circle with a radius of 6....can you help me get started?

Sketch the problem.

Let the triangle be ABC - and the center of the circle is O.

Join OA, OB and OC.

Then OA = OB = OC = ????

How much is angle ABC = ????

angle OBC = 1/2(angle ABC ) = ???

Now calculate side BC = 2 * OB * cos(OBC) = AB = CA

Perimeter = AB + BC + CA