The values are given by the circle C, and .

Here MPO is right angled triangle.

Hence .

Use pythagorean theorem to find x.

                       (Apply Pythagorean theorem)

                           (Substitute , and )

                                (Evaluate powers)

             (Subtract 256 from each side)

                                         (Subtract: )

                                            (Apply squart root of each side)

                                                (Because x is length)

Since , and .

                        (Apply Converse of pythagorean theorem)                           (Substitute , and )

                                  (Evaluate powers)

                                          (Add: )

Because , is a right angled triangle.

So,PR is tangent to circle C.