BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

its vertices do not send any diagonal

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
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

its vertices do not send any diagonal

by sanju09 » Tue May 24, 2011 1:56 am
How many diagonals does a polygon with 18 sides have if three of its vertices do not send any diagonal? Use the formula: number of diagonals = n (n - 3)/2 where n is the number of sides. Each vertex sends of n - 3 diagonals.
(A) 90
(B) 126
(C) 210
(D) 264
(E) 306


[spoiler]Source: Eric's collection on BTG


OA A[/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
Top
Source: — Problem Solving |
Legendary Member
Posts: 1448
Joined: Tue May 17, 2011 9:55 am
Location: India
Thanked: 375 times
Followed by:53 members

by Frankenstein » Tue May 24, 2011 3:34 am
Hi,
Three vertices of 18-sided polygon are not sending any diagonals. So, effectively there are only 15 vertices sending diagonals. So, the number of diagonals =15.(15-3)/2 = 90

Cheers!
Top
Post new topic Post Reply
• Page 1 of 1