CAT Practice : Coordinate Geometry

You are here: Home  CAT Questionbank   CAT Quant  Geometry: Triangles  Question 31
Finding the radius of the circle will help! Look at the triangles present!

Circumference of a circle

    Q.31: What is the circumference of the below circle given that AB is the diameter and XY is perpendicular to AB?

    1. 8π cm
    2. π cm
    3. 34π/3 cm
    4. π /3 cm


  • Correct Answer
    Choice (C). 34π/3 cm

Detailed Solution

Join AY and let AX = a
Diameter = a + 3
Since AB is the diameter, ∠AYB = 90
Since XY is perpendicular to AB, ∠BXY = 90
BY = =

Consider triangles ABY and BXY
∠ABY is same as ∠XBY and both the triangles are right angled
Therefore they are similar triangles and sides are proportional!
(a+3)/ = /3
3a + 9 = 34
or a = 25/3
Diameter = 25/3 + 3 = 34/3
Circumference = π*d = 34π/3 cm

Correct Answer: (C). 34π/3 cm

Our Online Course, Now on Google Playstore!

2IIM's App

Fully Functional Course on Mobile

All features of the online course, including the classes, discussion board, quizes and more, on a mobile platform.

Cache Content for Offline Viewing

Download videos onto your mobile so you can learn on the fly, even when the network gets choppy!

Get it on Google Play
Geometry is probably the most vital topic as far as CAT preparation is concerned. Geometry sets the stage for Trigonometry, Cogeo and Mensuration as well.