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Geometry question

Expert replies
Source: — Problem Solving |

by Brent@GMATPrepNow » Mon Nov 02, 2015 8:43 am
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In the figure above, points P and Q lie on the circle with center O. What is the value of S?

a) 1/2
b) 1
c) √2
d) √3
e) (√2)/2
Here's one approach:
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So, s = 1
Answer: B

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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by [email protected] » Mon Nov 02, 2015 10:20 am
Hi april24,

Brent's approach to solving this question is exactly how I wouldn't have done it, so I won't rehash that explanation. Instead I'll point out the patterns and "hints" that were in the original drawing (and that you should be on the lookout for when dealing with similar questions).

1) Any time you see a diagonal line segment on a graph, you can draw a right triangle using that line as the hypoteneuse.

2) Right triangles on the GMAT are almost always pattern-based (angles or sides; at the very least, the Pythagorean Theorem). Here, we have a 1 and a √3, so we should be thinking 30/60/90.

3) Radii have the same length no matter what direction they go in.

4) Lines "add up" to 180 degrees.

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
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by akash singhal » Tue Nov 03, 2015 11:44 pm
april24 wrote:Please suggest the best approach to answer this question.
Answer S=1
Use 30-60-90 Approach
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