CAT 2019 Slot 1 — QA Question 27
Basics of CirclesEasy
AB is a diameter of a circle of radius 5 cm. Let P and Q be two points on the circle so that the length of PB is 6 cm, and the length of AP is twice that of AQ. Then the length, in cm, of QB is nearest to
Answer & solution
Correct answer: 9.1
- A
7.8
- B
8.5
- C
9.3
9.1
Solution
Easy
An angle in a semicircle is a right angle, so both and are right-angled at and . Apply Pythagoras in to find (hence ), then again in to get .
Radius diameter . Given and . Let , so .
1
Right angle at . is a diameter, so . Pythagoras in :
2
Right angle at . Likewise . Pythagoras in with :