PT is a tangent to a circle whose centre is 0, and where T is a point on the circle. If PT=12 cm and PO=13cm, then find the radius of the circle.

PT = 12 cm (tangent to the circle from point P)

PO = 13 cm (distance from point P to the center O of the circle)

For a tangent PT to a circle from a point P outside the circle, the radius OT drawn to the tangent at the point of contact T is perpendicular to the tangent. This forms a right triangle △POT where:

​$$PO^2 = PT^2 + OT^2$$​​

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