Two chords AB=4 and AC=7 are given in circle. The angle between them is 60. Calculate radius.
1. Calculate the 3rd side as described by undefined.
2. Use the theorem of the circumscribed circels of a triangle: The central angle is twice as large as the angle at the circle. Use the right triangle at the center of the circle and half of the 3rd side to calculate the length of the radius: