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geometry intermediate

Problem

Let be a diameter of a circle centered at . Let be a point on the circle, and let the tangent at intersect the tangent at and at and , respectively. If , find , in degrees.

problem
Solution
Both angles and subtend arc , so . Triangle is isosceles with , since these are tangent from the same point to the same circle, so .

Finally, since is a diameter, so . Therefore, .
Final answer
47^\circ