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# DS - Geometry

Author Message
Manager
Joined: 12 Apr 2006
Posts: 204
Location: India

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01 May 2009, 06:16
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I was completely lost on this problem. Please explain the emthod to solve. TIA
Attachment:

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--== Message from GMAT Club Team ==--

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Manager
Joined: 19 Oct 2008
Posts: 87

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01 May 2009, 08:48
1
The answer is D. The trick is to recognize that angle PRS + Angle PRQ = 180. Given

PRS + PRQ = 180 (Equation 1)
RPS + PRS = 90 (Equation 2)
PQR+ QPR + PRQ = 180 (Equation 3)

Question is asking PRS - PQR= ?

1) QPR = 30
PQR+30+PRQ=180 (equation 3)
PQR+PRQ=150
deduct from equation 1
PRS-PQR = 30 Sufficient

2) PQR +PRQ = 150
Subtract from equation 1
PRS - PQR = 30 Sufficient

Both are sufficient, hence D.
Manager
Joined: 12 Apr 2006
Posts: 204
Location: India

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01 May 2009, 23:01
Accountant wrote:
The answer is D. The trick is to recognize that angle PRS + Angle PRQ = 180. Given

Thanks for the explanation
Manager
Joined: 08 Feb 2009
Posts: 140
Schools: Anderson

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02 May 2009, 09:46
Statement 1 is sufficient by Exterior Angle Theorem (http://en.wikipedia.org/wiki/Exterior_angle_theorem)

Statement is implying the Angle QPR = 30, from which point you can apply Exterior Angle theorem.
Manager
Joined: 19 Aug 2006
Posts: 226

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02 May 2009, 12:33
Accountant wrote:
The answer is D. The trick is to recognize that angle PRS + Angle PRQ = 180. Given

PRS + PRQ = 180 (Equation 1)
RPS + PRS = 90 (Equation 2)
PQR+ QPR + PRQ = 180 (Equation 3)

Question is asking PRS - PQR= ?

1) QPR = 30
PQR+30+PRQ=180 (equation 3)
PQR+PRQ=150
deduct from equation 1
PRS-PQR = 30 Sufficient

2) PQR +PRQ = 150
Subtract from equation 1
PRS - PQR = 30 Sufficient

Both are sufficient, hence D.

Could you explain why this equation is true: RPS + PRS = 90 (Equation 2)
Based on what?
Manager
Joined: 05 Jan 2009
Posts: 73

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02 May 2009, 13:11
Hi,
Good question! Just wondering about the source. where did you get it from?
Manager
Joined: 19 Aug 2006
Posts: 226

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02 May 2009, 13:14
goldeneagle94 wrote:
peraspera wrote:
Accountant wrote:
The answer is D. The trick is to recognize that angle PRS + Angle PRQ = 180. Given

PRS + PRQ = 180 (Equation 1)
RPS + PRS = 90 (Equation 2)
PQR+ QPR + PRQ = 180 (Equation 3)

Question is asking PRS - PQR= ?

1) QPR = 30
PQR+30+PRQ=180 (equation 3)
PQR+PRQ=150
deduct from equation 1
PRS-PQR = 30 Sufficient

2) PQR +PRQ = 150
Subtract from equation 1
PRS - PQR = 30 Sufficient

Both are sufficient, hence D.

Could you explain why this equation is true: RPS + PRS = 90 (Equation 2)
Based on what?

Because RSP = 90

Yes, I read it wrong. Of course.

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: DS - Geometry   [#permalink] 02 May 2009, 13:14
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