length of the third side

This topic has expert replies
Senior | Next Rank: 100 Posts
Posts: 83
Joined: Tue Mar 31, 2009 11:03 am
Thanked: 3 times

length of the third side

by EricKryk » Fri Jan 24, 2014 9:27 am
If 3 and 8 are the lengths of two sides of a triangular region, which of the following can be the length of the third side?

_______________I. 5
_______________II. 8
_______________III. 11

A) II only
B) III only
C) I and II only
D) II and III only
E) I, II, and III

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Fri Jan 24, 2014 9:31 am
EricKryk wrote:If 3 and 8 are the lengths of two sides of a triangular region, which of the following can be the length of the third side?

_______________I. 5
_______________II. 8
_______________III. 11

A) II only
B) III only
C) I and II only
D) II and III only
E) I, II, and III
IMPORTANT RULE: If two sides of a triangle have lengths A and B, then . . .
difference between sides A and B < third side < sum of sides A and B

So, for this question: 8 - 3 < third side < 8 + 3
Simplify: 5 < third side < 11

So, the third side must be LONGER than 5 and SHORTER than 11
Answer: A

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image

User avatar
GMAT Instructor
Posts: 1052
Joined: Fri May 21, 2010 1:30 am
Thanked: 335 times
Followed by:98 members

by Patrick_GMATFix » Fri Jan 24, 2014 9:41 am
the length of the 3rd side of any triangle is greater than the positive difference between the other two side lengths, but less than the sum of the other two side lengths. The solution below is taken from the GMATFix App.

Image

-Patrick
  • Ask me about tutoring.