endpoints at coordinates

This topic has expert replies
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 am
Location: India
Thanked: 267 times
Followed by:80 members
GMAT Score:760

endpoints at coordinates

by sanju09 » Wed May 02, 2012 3:12 am
The base of an isosceles triangle has endpoints at coordinates (1, 1) and (13, 1). The area of the triangle is 48. The third point of the triangle could be located at:
(A) (6, -6)
(B) (6, -11)
(C) (7, 9)
(D) (7, -11)
(E) (13, 13)



https://www.crushthetest.com
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pm
Location: Milpitas, CA
Thanked: 1854 times
Followed by:523 members
GMAT Score:770

by Anurag@Gurome » Wed May 02, 2012 4:31 am
sanju09 wrote:The base of an isosceles triangle has endpoints at coordinates (1, 1) and (13, 1). The area of the triangle is 48. The third point of the triangle could be located at:
(A) (6, -6)
(B) (6, -11)
(C) (7, 9)
(D) (7, -11)
(E) (13, 13)

https://www.crushthetest.com
Length of the base = √[(13 - 1)² + (1 - 1)²] = √(12²) = 12
Area of the triangle = (1/2) * base * height
48 = (1/2) * 12 * height
48 = 6 * height
height = 8
Now the altitude to the base of an isosceles triangle bisects the base.
Midpoint of (1, 1) and (13, 1) = (7, 1)
Let the coordinates of the 3rd point = (a, b)
Then √[(a - 7)² + (b - 1)²] = 8
Only answer choice (7, 9) satisfies the above equation.

The correct answer is C.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/