a triangle have 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

a triangle have coordinates

by sanju09 » Fri Oct 08, 2010 3:37 am
In the xy-plane, the vertices of a triangle have coordinates (0, 0), (3, 3), and (7, 0). What is the perimeter of the triangle?
(A) 13
(B) √34
(C) √43
(D) 7 + 6 √2
(E) 12 + 3 √2


[spoiler]Source: https://www.gmatcram.com[/spoiler]
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: 1179
Joined: Sun Apr 11, 2010 9:07 pm
Location: Milpitas, CA
Thanked: 447 times
Followed by:88 members

by Rahul@gurome » Fri Oct 08, 2010 4:11 am
Distance between (0, 0) and (3, 3) = √[(3-0)^2 + (3-0)^2] = √18
Distance between (0, 0) and (7, 0) = √[(7-0)^2 + (0-0)^2] = √49 = 7
Distance between (3, 3) and (7, 0) = √[(7-3)^2 + (0-3)^2] = √(16+9) = 5
Perimeter of triangle = 5 + 7 + √18 = 12 + 3√2

[spoiler]The correct answer is (E).[/spoiler]
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)

User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Fri Oct 08, 2010 4:54 am
sanju09 wrote:In the xy-plane, the vertices of a triangle have coordinates (0, 0), (3, 3), and (7, 0). What is the perimeter of the triangle?
(A) 13
(B) √34
(C) √43
(D) 7 + 6 √2
(E) 12 + 3 √2


[spoiler]Source: https://www.gmatcram.com[/spoiler]
Distance from (0,0) to (7,0) = 7.
(3,3) and (7,0) form a side of 3 and a side of 4 in a 3:4:5 right triangle, so the distance between them = 5.
7+5 = 12, which is only in answer choice E. (Since the 3rd side is longer than 1, we know that 12+1=13 in answer choice A cannot be correct.)

The correct answer is E.

For the curious, (0,0) to (3,3) from two sides of 3 in a 45:45:90 triangle -- in which the sides are proportioned s:s:s√2 -- so the distance between them is 3√2.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3