SSC CGL 2024 PYQ — Question 74

SSC CGL - 26 Sep 2024 - Shift 3 • Quantitative Aptitude • Q74

A secant PAB is drawn from an external point P to the circle with the centre at O, intersecting it at A and B. If OP = 17 cm, PA = 12 cm and PB = 22.5 cm, then the radius of the circle is:

Show answer & explanation

Correct answer: D

Explanation

The correct answer is option 4 i.e.  19\sqrt{19} cm.

The product of one whole secant segment and its external segment is equal to the product of the other whole secant segment and its external segment.

OP = 17 cm, PA = 12 cm and PB = 22.5 cm

Here, OD = OC = r cm (Radius)

So, PA × PB = PC × PD

⇒ PA × PB = (OP - OC)(OP + OD)

⇒ 12 × 22.5 = (17 - r)(17 + r) = 172 - r2

⇒ 270 = 289 - r2

⇒ r2 = 289 - 270 = 19

⇒ r = √19

Therefore, the radius of the circle is √19 cm.