Answer Keys.

First of all, let's draw two new segments.

Since two tangents drawn from a point is equal in length, we have .

So, is an isosceles right triangle.

Since an angle inside an arc is equal to the circumference angle of that arc, we have .

So, is an isosceles right triangle.

Solution.

Let's mark some angles on the diagram.

Then, we observe newly made triangles follow this.

Let .

Now the ratio of the corresponding sides is equal to each other.

Answer:

Solution.