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

In the given diagram, the circle touches the y-axis at the

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Moderator
Posts: 7187
Joined: Thu Sep 07, 2017 4:43 pmFollowed by: 23 members
by BTGmoderatorDC » Sat Nov 17, 2018 8:12 pm
Timer
00:00
Your answer
Difficulty–

right wrong

Pick an answer to see how members did

Image

$$In\ the\ given\ diagram,\ the\ circle\ touches\ the\ y-axis\ at\ the\ point\ K\ whose\ coordinate\ is\ (0,7).$$
$$If\ the\ area\ of\ triangle\ CKO\ is\ 21\ units^2,\ where\ C\ is\ the\ center\ of\ the\ circle,\ find\ the\ area\ of\ the\ circle.$$

A. 16Ï€
B. 21Ï€
C. 24Ï€
D. 36Ï€
E. 49Ï€

OA D

Source: e-GMAT
Top
Join the discussion
Source: — Problem Solving |
User avatar
GMAT Instructor
Posts: 1449
Joined: Sat Oct 09, 2010 2:16 pmFollowed by: 33 members
Thanked: 59 times

by fskilnik@GMATH » Sun Nov 18, 2018 6:20 am
BTGmoderatorDC wrote:Image

$$In\ the\ given\ diagram,\ the\ circle\ touches\ the\ y-axis\ at\ the\ point\ K\ whose\ coordinate\ is\ (0,7).$$
$$If\ the\ area\ of\ triangle\ CKO\ is\ 21\ units^2,\ where\ C\ is\ the\ center\ of\ the\ circle,\ find\ the\ area\ of\ the\ circle.$$

A. 16Ï€
B. 21Ï€
C. 24Ï€
D. 36Ï€
E. 49Ï€
Source: e-GMAT
$$? = \pi {r^2}$$

Image

$${{7 \cdot r} \over 2} = 21\,\,\,\,\, \Rightarrow \,\,\,\,\,r = 2 \cdot 3\,\,\,\,\, \Rightarrow \,\,\,\,\,? = 36\pi $$


This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.
Fabio Skilnik :: GMATH method creator ( Math for the GMAT)
English-speakers :: https://www.gmath.net
Portuguese-speakers :: https://www.gmath.com.br
Top
Join the discussion

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3008
Joined: Mon Aug 22, 2016 6:19 amFollowed by: 34 members
Location: Grand Central / New York
Thanked: 470 times

by Jay@ManhattanReview » Tue Nov 20, 2018 10:18 pm
BTGmoderatorDC wrote:Image

$$In\ the\ given\ diagram,\ the\ circle\ touches\ the\ y-axis\ at\ the\ point\ K\ whose\ coordinate\ is\ (0,7).$$
$$If\ the\ area\ of\ triangle\ CKO\ is\ 21\ units^2,\ where\ C\ is\ the\ center\ of\ the\ circle,\ find\ the\ area\ of\ the\ circle.$$

A. 16π
B. 21π
C. 24π
D. 36π
E. 49π

OA D

Source: e-GMAT
To get the area of the circle, we need the value of its radius.

Since the circle touches Y-axis at point K, Y-axis would be a tangent to the circle and CK would be the radius.

Thus, ∆OCK is a right-angled triangle with OK is its bases and CK is its altitude (height).

Thus, area of ∆OCK = 1/2*OK*CK

=> 21 = 1/2*7*CK; note that OK is y coordinate of the point K.

=> CK = Radius of the circle = 6 units

Thus, area of the circle = π*Radius^2 = π*6^2 = 36π

The correct answer: D

Hope this helps!

-Jay
_________________
Manhattan Review GRE Prep

Locations: GMAT Classes Boston | GRE Prep Course NYC | GRE Prep Dallas | SAT Prep Classes Houston | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
Top
Join the discussion