Math questions and topics from the Official Guide book. Please try to follow the posting pattern (e.g. OG - pg. 181 - #8) to allow for easier searches. Questions posted in the GRE Math section regarding the OG have been moved here.
johnhurford
 
Posts: 11
Joined: Mon Dec 22, 2014 8:36 am
 

OG pg 261 #11 d

by johnhurford Sun Apr 26, 2015 8:47 pm

Question on pg 261 #11 d.

How do you arrive at the answer 2*sqrt(29)?

Pythagorean theory doesn't seem to work for me (e.g. 12^2 + (2*sqrt(5))^2 = c^2 OR (2*sqrt(5))^2 +b^2 = 12^2).

Thanks,

John
tommywallach
Manhattan Prep Staff
 
Posts: 1917
Joined: Thu Mar 31, 2011 11:18 am
 

Re: OG pg 261 #11 d

by tommywallach Fri May 01, 2015 3:06 pm

Hey John,

The diagonal is the hypotenuse of a triangle which has a height of 4 (see the dotted line all the way to the right), and a base of 10. Looks like you're saying the base is 12, but we have to subtract 2 (it's symmetrical, so we can use the 2 on the right to find the portion on the left).

10^2 + 4^2 = 116

rt. 116 = rt. 4 * rt. 29 = 2 * rt. 29

-t