SSC CGL 2020 PYQ — Question 67

SSC CGL - 4th March 2020 Shift 1 • Quantitative Aptitude • Q67

In ΔABC, AB = AC. A circle drawn through B touches AC at D and intersect AB at P. If D is the mid point of AC and AP is 2.5 cm, then AB is equal to:

Show answer & explanation

Correct answer: B

Explanation

The correct answer is Option 2 i.e 10 cm.

Understanding/Application

D is the mid-point of AC so,

AD = AC/2

But also given - 

AC = AB

AD = AB/2 .....(1)

AD is a tangent and APB is a secant. So the tangent secant theorem can be applied -

AD2 = AP × AB

⇒ (AB/2)2 = AP × AB

⇒ AB2/4 = 2.5 × AB

⇒ AB = 10 cm