area

Expert replies

ketkoag: Legendary Member; Posts: 876; Joined: Thu Apr 10, 2008 8:14 am; Thanked: 13 times

by ketkoag » Wed May 06, 2009 12:51 am

An equilateral triangle that has an area of 9 3^1/2 is inscribed in a circle. What is the
area of the circle?
A . 6pi B. 9pi C. 12 pi D. 9pi 3^1/2 E. 18pi 3^1/2

Like this post

Source: Beat The GMAT — Problem Solving | Wed May 06, 2009 12:51 am

sureshbala: Master | Next Rank: 500 Posts; Posts: 319; Joined: Wed Feb 04, 2009 10:32 amFollowed by: 9 members; Location: Delhi; Thanked: 84 times

by sureshbala » Wed May 06, 2009 1:58 am

If an equilateral triangle is inscribed in a circle, 2/3 rd the height of the triangle will be the radius of the circle.

Let "a" be the side of the equilateral triangle.

Given sqrt(3)/4 x a^2 = 9 x sqrt(3)

Hence a^2=36

Thus a = 6.

Now height of the equilateral triangle = sqrt(3)/2 x a = sqrt(3)/2 x 6

Hence radius of the circle = 2/3 x sqrt(3)/2 x 6 = 2 x sqrt(3)

Hence area of the circle = 12 pi

Averages Accelerated: Complete guide to solve Averages Quickly

Data Sufficiency for 780+ Aspirants

Problem Solving for 780+ Aspirants.

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review