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

Properties of cicles

Expert replies
by Mission2012 » Sun Sep 01, 2013 7:40 pm
Is it true -

Only way two perpendicular lines can be tangent to the same circle if the arc they form represent exactly one quarter of a circle.
If you find my post useful -> please click on "Thanks"
Join the discussion
Source: — Problem Solving |

by [email protected] » Sun Sep 01, 2013 10:32 pm
Hi Mission2012,

I'm going to "tweak" your sentence a bit, but I can tell you that the idea that you're talking about IS true.

When two lines that are tangent to a circle and perpendicular to one another, then the arc of the circle that exists between them will be 1/4 of the circumference.

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Join the discussion

by sanjoy18 » Sun Sep 01, 2013 10:39 pm
actually two perpendicular tangents form an angle of 90 at center of circle
therefore length of minor arc 90/360=1/4
hence proved
Join the discussion

by Mike@Magoosh » Mon Sep 02, 2013 10:33 am
Mission2012 wrote:Is it true -

Only way two perpendicular lines can be tangent to the same circle if the arc they form represent exactly one quarter of a circle.
Dear Mission2012,
I happy to add my two cents. :-)

Yes, this statement is true. For example, suppose the circle has a center O, the two tangents are tangent at points A & C, and the tangents intersect at point B outside of the circle. We already know angles A & C, where the radius meets a tangent, are 90 degree angles. If B is also a right angle, that's a quadrilateral with three right angles --- since the sum of the angles must be 360 degrees, then if three of the angles are right angles, the fourth must be a right angle also. In fact, because all the lengths are equal, quadrilateral OABC has to be a square.

This is a rare case in which a relatively simple specification guarantees the quadrilateral formed is a square. Normally, guaranteeing something is a square is not so easy. See:
https://magoosh.com/gmat/2012/gmat-geome ... -a-square/

Does all this make sense?
Mike :-)
Magoosh GMAT Instructor
https://gmat.magoosh.com/
Join the discussion