Area of an equilateral triangle

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
This topic has expert replies
Source: — Quantitative Reasoning |

User avatar
MBA Admissions Consultant
Posts: 1090
Joined: Wed May 27, 2009 4:06 am
Thanked: 175 times
Followed by:68 members
GMAT Score:750

by Bryant@VeritasPrep » Mon Aug 10, 2009 5:20 pm
the height of an equilateral triangle is equal to the sin(Angle)times B where B is the length of one of its sides. Since equilateral triangle has all three angles of 60 degrees, you can take the height divided by Sin (60) to get the base length, then employ the traditional 1/2 b times h to get area. hope this helps.
Bryant Michaels
MBA Admissions Consultant


Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options

Junior | Next Rank: 30 Posts
Posts: 21
Joined: Tue Aug 19, 2008 4:58 am

by vani_13in » Mon Aug 10, 2009 5:47 pm
Thanks alot!. It really helped

Newbie | Next Rank: 10 Posts
Posts: 6
Joined: Sat May 31, 2008 4:19 am

by knightwalker » Mon Aug 31, 2009 6:43 am
If you want a shortcut for when you have only the side of an equilateral triangle, the height is always ((sq.root3)/2)*s where s is the side of the triangle and thus the area is always ((sq.root3)/4)*s^2

Master | Next Rank: 500 Posts
Posts: 125
Joined: Sun Sep 16, 2007 1:38 pm
Thanked: 6 times

Re: Area of an equilateral triangle

by chetanojha » Mon Aug 31, 2009 7:35 am
vani_13in wrote:How do I find area of an equilateral triangle if I know the height ?

V
An equilateral triangle can be split into two 30-60-90 triangle which have relationship of 1:sqrt(3):2. If you know any one side...you can find all the remaining sides and hence area.

User avatar
GMAT Instructor
Posts: 80
Joined: Wed Aug 12, 2009 8:49 pm
Location: San Francisco, CA
Thanked: 16 times

by grockit_jake » Mon Aug 31, 2009 9:03 am
If you don't know the height, but rather just a SIDE, you can use the formula:

Area = s^2 * sqrt(3)/4
Jake Becker
Academic Director
Grockit Test Prep
https://www.grockit.com