A chord AB of length 13 cm subtends an angle of 67° at the circumference of a circle center O. Find the radius of the circle

Answer 1

I made a sketch, which you obviously have done as well.
let the radius be r, then I see that
r^2 + r^2 - 2(r)(r)cos67° = 13^2
r^2 (2 - 2cos67°) = 169
find r