Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.

See classes
Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep

Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.

★★★★★5.0563 reviews
GMATLiveTeachStarts Nov 22
Josh Braslow, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Josh Braslow, 20+ years in test prep

Nov 22 · Josh Braslow
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemandStart anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

EXECUTIVE ASSESSMENT

with

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget Test Prep
GMATOnDemandStart anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 563 reviewsTarget Test Prep

Special Triangles Question

Problem Solving — algebra and arithmetic
Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 20
Joined: Thu Oct 09, 2008 10:35 am
by giatch » Mon Dec 29, 2008 12:58 pm
Could someone please clear up something for me..

For the special triangles, i.e.

1) 3:4:5 with side 5 opposite the right angle
2)12:5:3 with 13 opposite the right angle

What are the measure of the other two angles for these two respective triangles?

Does it matter? Will it be the 30:60:90 triangle or something else?
Top
Join the discussion
Source: — Quantitative Reasoning |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2623
Joined: Mon Jun 02, 2008 3:17 amFollowed by: 355 members
Location: Montreal
Thanked: 1090 times
GMAT Score:780

by Ian Stewart » Mon Dec 29, 2008 1:17 pm
To work out the angles in a 3-4-5 or 5-12-13 triangle, you'd need to use trigonometry (sine, cosine, etc) - in other words, not something you'd ever need for the GMAT. If I remember right, the 3-4-5 has angles something like 38-52-90, rounded to the nearest integer, but you certainly don't need to know that for the test. They are certainly not 30-60-90 triangles, since every 30-60-90 triangle has sides which are in a 1-root(3)-2 ratio.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com
Top
Join the discussion
Senior | Next Rank: 100 Posts
Posts: 87
Joined: Tue Dec 23, 2008 11:06 pm
Thanked: 2 times

by rajataga » Sun Jan 04, 2009 8:14 pm
The only thing that you might need to keep in mind is that both the groups that you have given are 'pythagorean triplets'. Meaning they are the sides of a triangle forming a right angled triangle.

I've seen in some sums it is helpful to keep in mind the basic pythagorean triplets

THe angle opposite the largest side will always be the right angle.

So, if you see these sides for a triangle, you know that it is a right angled triangle, and also the right angle.
Top
Join the discussion