From a point T, the length of the tangent to a circle is 32 cm and the distance of T from the centre is 40 cm. The diameter (in cm) of the circle is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 48.
According to the given question,

Let the tangent from T meets the circle at P, O be the center of the circle and r be the radius of the circle.
The line from the center of the circle to the point where tangent meets the circle makes as angle of 90° with the tangent.
Now, in the above figure, in triangle OPT, ∠OPT is a right angle.
Applying Pythagoras theorem in triangle OPT,
OP2 + PT2 = OT2
⇒ r2 + 322 = 402
⇒ r2 + 1024 = 1600
⇒ r2 = 576
⇒ r = 24
Now, diameter = 2r
⇒ 2 × 24 = 48
Hence the diameter (in cm) of the circle is 48.