Math questions from any Manhattan Prep GMAT Computer Adaptive Test.
afashoro
Course Students
 
Posts: 7
Joined: Fri Jun 06, 2008 11:02 pm
 

A Cute Triangle

by afashoro Thu Sep 09, 2010 12:32 am

What is the degree measure of angle a?
(1) b + c = 287 degrees
(2) d + e = 269 degrees

I understand how to solve this but for some reason I'm struggling to figure out a quick way to solve this problem in =< 2 minutes.
gokul_nair1984
Students
 
Posts: 170
Joined: Tue Apr 13, 2010 8:07 am
 

Re: A Cute Triangle

by gokul_nair1984 Thu Sep 09, 2010 1:03 am

Please post the complete problem (with figure if possible)
mschwrtz
ManhattanGMAT Staff
 
Posts: 498
Joined: Tue Dec 14, 2004 1:03 pm
 

Re: A Cute Triangle

by mschwrtz Sat Sep 18, 2010 1:50 am

There may be better ways--feel free to jump in with any expertise--but you can go to an image-hosting site like postimage.org to, well, post images.
sivai87
Students
 
Posts: 15
Joined: Wed Dec 01, 2010 4:10 am
Location: Chennai, India
 

Re: A Cute Triangle

by sivai87 Thu Dec 02, 2010 4:58 am

Hi.. Please find the image below.. Help needed on this problem.. Thanks in advacne..

Image

Kind Regards,
Sivai
jnelson0612
ManhattanGMAT Staff
 
Posts: 2664
Joined: Fri Feb 05, 2010 10:57 am
 

Re: A Cute Triangle

by jnelson0612 Fri Dec 03, 2010 2:59 am

sival,
I think that the quickest and easiest way to do this is to rephrase. The question asks the degree measure of angle a, but since we know that opposite angles are equal it could also be asking the degree measure of angle e.

We also know that e + f + g = 180, so e=180 - (f+g). In other words, if I know (f+g) I can determine e, which is equal to a. So my new rephrased question is what is (f+g)? Or what is the degree value of angle e? Either will get me to the degree value of angle a.

1) b+c = 287 degrees. I know that (b+f) and (c+g) each equal 180 because they are straight lines. Rewrite as (b+c) + (f+g) = 360. Sub 287 in for (b+c) and you have 287 + (f+g) = 360. Thus, (f+g) = 73. Sufficient.

2) d+e = 289 degrees. This is not helpful. You could plug in different values for d and e into the diagram. For example, I could say:
d=150
e=139
f=30
g=11

or I could say:
d=155
e=134
f=25
g=21

Either of these scenarios fits all geometric rules; thus, this information does not help us determine the degree value of angle a. Insufficient.
Jamie Nelson
ManhattanGMAT Instructor
sivai87
Students
 
Posts: 15
Joined: Wed Dec 01, 2010 4:10 am
Location: Chennai, India
 

Re: A Cute Triangle

by sivai87 Sun Dec 05, 2010 8:03 am

Thanks Jamie
jnelson0612
ManhattanGMAT Staff
 
Posts: 2664
Joined: Fri Feb 05, 2010 10:57 am
 

Re: A Cute Triangle

by jnelson0612 Mon Dec 06, 2010 7:41 am

My pleasure sival.
Jamie Nelson
ManhattanGMAT Instructor