Find all School-related info fast with the new School-Specific MBA Forum

It is currently 21 Sep 2014, 22:21

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

PS # half circle

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
SVP
SVP
User avatar
Joined: 28 May 2005
Posts: 1743
Location: Dhaka
Followers: 6

Kudos [?]: 41 [0], given: 0

GMAT Tests User
PS # half circle [#permalink] New post 02 Nov 2005, 13:26
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 1 sessions
please explain...
Attachments

half circle.jpg
half circle.jpg [ 9.14 KiB | Viewed 697 times ]


_________________

hey ya......

Manager
Manager
avatar
Joined: 20 Mar 2005
Posts: 201
Location: Colombia, South America
Followers: 1

Kudos [?]: 6 [0], given: 0

GMAT Tests User
 [#permalink] New post 02 Nov 2005, 13:39
it looks like it is sqrt(3) as the angle POQ is 90 degrees and therefore it is a reflection.

another way to think about it
what is the result of rotating a radius 90 degrees along the circumference.
in that case what is the effect in the cosine?

make sense?
Current Student
avatar
Joined: 28 Dec 2004
Posts: 3404
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 160 [0], given: 2

GMAT Tests User
 [#permalink] New post 02 Nov 2005, 13:49
can you repost the question..not sure what we are asking for s, t?
Manager
Manager
avatar
Joined: 04 Oct 2005
Posts: 246
Followers: 1

Kudos [?]: 15 [0], given: 0

GMAT Tests User
 [#permalink] New post 02 Nov 2005, 13:56
I get 2sqrt2 - sqrt3... which is neither of the choices...

We know that the radii must be the same for both. We have two triangles...
one with legs of length 1 and sqrt3.... a similar triangle, thus the 3rd length, or the radius, must be 2.
The second triangle with the 90┬░ angle is then a 45-45-90. So the line connecting points P and Q should have a length of sqrt2.

Deduct the length of the x coordinate from the first point, gives you the x coordinate of the second.

:EDIT:
just realized, that this only works when the line PQ is parallel to the x axis... which must not be the case.
Intern
Intern
avatar
Joined: 22 Mar 2005
Posts: 39
Location: Houston
Followers: 0

Kudos [?]: 0 [0], given: 0

 [#permalink] New post 02 Nov 2005, 17:29
Wow, this is a great one. Don't let the diagram fool you here.

First, as was previously mentioned you can see that the radius is 2.

Now calculate the distance between the two points by drawing a line between them. Obviously the distance between them is equal to the hypotenuse of the triangle with the two radii as its legs.

So distance between them = sqrt(2^2+2^2) = sqrt(8)

Now the distance formula between to points says that:
DF = (s+sqrt(3))^2+(t-1)^2 had better equal sqrt(8)^2 = 8 as well.

We need one more equation that relates s and t and we are ready to go.
That equation of course is that s^2+t^2 = 2^2 (eqn of the circle)

Now solve for t^2 = 4 - s^2 and t = sqrt(4-s^2)

Now go back to the distance formula above (DF), multipy it out and then plug in the expressions above for t^2 and t. Now solve for s and you will see that s = 1 and t = sqrt(3).

So the drawing is playing a little trick as the y axis isn't really bisecting the 90 deg angle. As a quick check if it were the other way around and s = sqrt(3) and y = 1, then the distance between the points would simply be sqrt(3) + sqrt(3) = 2sqrt(3) which does not equal sqrt(8) (or 2sqrt(2)).
SVP
SVP
User avatar
Joined: 24 Sep 2005
Posts: 1898
Followers: 10

Kudos [?]: 104 [0], given: 0

GMAT Tests User
 [#permalink] New post 02 Nov 2005, 21:23
first of all, we should find the function of the two lines OP and OQ
from the coordinates provided we can easily find:
OP: y=-1/sqrt3 *x
OQ: y= t/s*x
Becoz OP and OQ are perpendicular --> t/s* ( -1/sqrt3)= -1
---> t/s= sqrt3--> t= s*sqrt3-->t^2= 3*s^2
We have:
s^2+t^2= (-sqrt3)^2+1^2= radius^2 = 4
--> s^2+3*s^2= 4 ---> s=- or + 1
becoz Q belongs to the II portion of the coordination --> s=1

Last edited by laxieqv on 02 Nov 2005, 21:30, edited 1 time in total.
Current Student
User avatar
Joined: 29 Jan 2005
Posts: 5252
Followers: 23

Kudos [?]: 133 [0], given: 0

GMAT Tests User Reviews Badge
 [#permalink] New post 02 Nov 2005, 21:30
S = sqrt3 by "eyeballing" and under 10 seconds 8-)

OA?
SVP
SVP
User avatar
Joined: 24 Sep 2005
Posts: 1898
Followers: 10

Kudos [?]: 104 [0], given: 0

GMAT Tests User
 [#permalink] New post 02 Nov 2005, 21:34
first of all, we should find the function of the two lines OP and OQ
from the coordinates provided we can easily find:
OP: y=-1/sqrt3 *x
OQ: y= t/s*x
Becoz OP and OQ are perpendicular --> t/s* ( -1/sqrt3)= -1
---> t/s= sqrt3--> t= s*sqrt3-->t^2= 3*s^2
We have:
s^2+t^2= (-sqrt3)^2+1^2= radius^2 = 4
--> s^2+3*s^2= 4 ---> s=- or + 1
becoz Q belongs to the II portion of the coordination --> s=1
SVP
SVP
User avatar
Joined: 28 May 2005
Posts: 1743
Location: Dhaka
Followers: 6

Kudos [?]: 41 [0], given: 0

GMAT Tests User
 [#permalink] New post 03 Nov 2005, 11:29
good job guys... OA is 1.

how long did it take you guys to do it... for me it took over 4 minutes... is it okay?
_________________

hey ya......

  [#permalink] 03 Nov 2005, 11:29
    Similar topics Author Replies Last post
Similar
Topics:
Experts publish their posts in the topic A circle is inscribed in a half circle with a diameter of GMATPASSION 3 23 Feb 2012, 00:53
inscribed circle in half circle bupbebeo 4 30 Aug 2010, 07:21
GMATPrep Question: Half Circle GMAT_700 1 10 Nov 2007, 17:21
PS- circle lan583 2 28 Sep 2006, 13:10
ps:circle macca 2 26 May 2006, 08:38
Display posts from previous: Sort by

PS # half circle

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

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®.