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

Redeem

GMAT Prep Trig Question

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
Legendary Member
Posts: 645
Joined: Wed Sep 05, 2007 4:37 am
Location: India
Thanked: 34 times
Followed by:5 members

by camitava » Fri Feb 15, 2008 8:10 am
davidforsberg, IMO D. Because, area of the equ. trainagle = sqrt(3) t^2 / 4.
area of square = s ^ 2.
Now sqrt(3) t^2 / 4 = s ^ 2
so t : s = ...

So IMO D.
Correct me If I am wrong


Regards,

Amitava
Top
Senior | Next Rank: 100 Posts
Posts: 83
Joined: Mon Oct 22, 2007 4:44 am
Thanked: 1 times

by its_me07 » Fri Feb 15, 2008 9:42 am
how do u solve this
t^2(sqrt3)/4=s^2 for t:s??????
Top
User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pm
Location: Toronto
Thanked: 1710 times
Followed by:614 members
GMAT Score:800

by Stuart@KaplanGMAT » Fri Feb 15, 2008 10:48 am
its_me07 wrote:how do u solve this
t^2(sqrt3)/4=s^2 for t:s??????
we want to get t/s, so we rearrange to that point.

t^2(sqrt3) = 4(s^2)

(t^2)/(s^2) = 4/sqrt3

t/s = sqrt(4/sqrt3)

t/s = 2/(4throot3)

choose (d)

[note: we don't worry about the negative solutions because in geometry they make no sense - if this were an algebra problem we would have had multiple answers]
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course
Top
Junior | Next Rank: 30 Posts
Posts: 19
Joined: Wed Feb 06, 2008 9:22 am

by gmatjoe » Sat Feb 16, 2008 1:51 am
Hi Everyone,

I've solved this problem as follows:

1) area square = s^2
2) area triangle = 1/2*b*h
3) and s^2=1/2*b*h

Main issue (and time consuming part) for me was to work out/simplify the expression for the area of the triangle and some knowledge of exponents:

4) b=t
5) find h with pythagoras: t^2=h^2+{(1/2)*t}^2 --> h^2=(1-1/4)*t^2, thus, h=t*sqrt(3/4) = t*sqrt(3)*(1/2)
6) plug it back in 3) gives: s^2=(1/2)*t*t*sqrt(3)*(1/2)=sqrt(3)*(1/4)*t^2
7) simplify further and then take root: t/s=2/sqrt(sqrt(3), answer is D.

Hope this helps. Cheers, Joe.
Top
Post new topic Post Reply
• Page 1 of 1