GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 15 Nov 2018, 08:56

Join Chat Room for Live Updates

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Events & Promotions

Events & Promotions in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
• Free GMAT Strategy Webinar

November 17, 2018

November 17, 2018

07:00 AM PST

09:00 AM PST

Nov. 17, 7 AM PST. Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.
• GMATbuster's Weekly GMAT Quant Quiz # 9

November 17, 2018

November 17, 2018

09:00 AM PST

11:00 AM PST

Join the Quiz Saturday November 17th, 9 AM PST. The Quiz will last approximately 2 hours. Make sure you are on time or you will be at a disadvantage.

The area of the circle in the figure above is 25π . What is the perime

Author Message
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 50610
The area of the circle in the figure above is 25π . What is the perime  [#permalink]

Show Tags

11 Sep 2018, 01:43
00:00

Difficulty:

25% (medium)

Question Stats:

69% (02:01) correct 31% (02:03) wrong based on 13 sessions

HideShow timer Statistics

The area of the circle in the figure above is 25π . What is the perimeter of the inscribed equilateral triangle?

A. $$15\sqrt{3}$$

B. 15

C. $$7.5\sqrt{3}$$

D. 7.5

E. $$2.5\sqrt{3}$$

Attachment:

image008 (1).jpg [ 3.25 KiB | Viewed 457 times ]

_________________
CEO
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2698
Location: India
GMAT: INSIGHT
WE: Education (Education)
The area of the circle in the figure above is 25π . What is the perime  [#permalink]

Show Tags

11 Sep 2018, 04:09
1
Bunuel wrote:

The area of the circle in the figure above is 25π . What is the perimeter of the inscribed equilateral triangle?

A. $$15\sqrt{3}$$

B. 15

C. $$7.5\sqrt{3}$$

D. 7.5

E. $$2.5\sqrt{3}$$

Attachment:
The attachment image008 (1).jpg is no longer available

Area pf the circle$$= πr^2 = 25π$$

i.e. $$r = 5$$

Join the vertices of triangle with centre of the circle so that equilateral triangle gets divided in three 120º-30º-30º triangles where 120º is teh angle drawn at the centre of the circle

Divide the 120º-30º-30º triangle into two 90º-30º-60º triangles which hahaev hypotenuse = 5
i.e. Side opposite to 30º = 5/2
and side opposite to 60º = 5√3/2 which is half of the length of the side of equilateral

i.e. side of equilateral triangle $$= 2*5√3/2 = 5√3$$
hence, Perimeter of the equilateral $$= 3*5√3 = 15√3$$

Attachments

File comment: www.GMATinsight.com

1.jpeg [ 32.8 KiB | Viewed 363 times ]

_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

Manager
Joined: 29 Jul 2018
Posts: 89
Concentration: Finance, Statistics
Re: The area of the circle in the figure above is 25π . What is the perime  [#permalink]

Show Tags

11 Sep 2018, 17:49
height of equi triangle is root3/2 side and median divides height in ratio 2:1 so 2/3*root3/2 side = 5( pi r^2 = pi*5^2)
so side = 5*3/root3
perimeter = 3 * side
5*3*root3*root3/root3 = 15*root3
Re: The area of the circle in the figure above is 25π . What is the perime &nbs [#permalink] 11 Sep 2018, 17:49
Display posts from previous: Sort by

The area of the circle in the figure above is 25π . What is the perime

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.