XY and XZ are tangents to a circle. ST is another tangent to the circle at the point R on the circle which intersects XY and XZ at S and T respectively, If XY = 9 cm and TX = 15 cm, then RT is:

Answer: Option D

XY = 9 cm, TX = 15 cm
⇒ We know
Length of tangents drawn from a point to the circle are equal
Therefore
XY = XZ = 9 cm, TZ = RT
TX = 15 cm
XZ + ZT = 15
ZT = 15 - 9 = 6
RT = ZT = 6 cm