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12-83.

In a circle, chord has length units, while . What is the area of the circle? Draw a diagram and show all work.  

The measure of the intercepted arc is equal to the measure of the central angle.

, because both are radii, so is isosceles.

Isosceles triangles have congruent base angles, so .


but ,
so

Circle, center C, with points, A, &, B, line segments from, C, to, B, from, C, to, A, from, A, to, B. Segment, A, B, labeled, 10, arc, A, B, labeled, 60 degrees.

 

Because the angles are all congruent, the triangle is equilateral.

So the length of the radius () is .