Given: A circle with radius OP = 9cm
A tangent PQ from a point Q at a distance of 15 cm
from the center OQ = 15 cm
Now in triangle POQ ∠p = 90°
OP2+PQ2-OQ2
2+PQ2 = 2
PQ2 = 2-2
PQ2=
PQ = √ = cm
Hence the length of the tangent = cm.