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Word of the Day
digress
Definition: (verb) to wander from the main path or the main topic.
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Math Teaser
Problem
If the cost of a 4-minute telephone call is $0.24, then the cost of a 15-minute call at the same rate is:
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SAT* Tip of the Day
So What?
Math questions involving two equations and two unknowns can usually be combined into one equation with one unknown.
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PSAT: Math Question #7

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Question:
 In the figure above,  P  is the center of a circle with area  9  π   , 
 points  Q  and  R  lie on the circle, and angle  a  is  45  °   . What is the 
 length of  QR?


Choices:
A. 3 2
B. 3
C. 9 2
D. 9
E. 18

The correct answer is (A).

To solve this one, we must first find the radius of the circle.

The correct answer is (A).

To solve this one, we must first find the radius of the circle.
 Knowing the area of the circle is  9  π   , we can find the radius 
 using the formula for the area of a circle: 

A  =   π  r2
9  π   =   π  r2
9  =  r2
3  =  r
a2  +  b2  =  c2
32  +  32  =  QR2
9  +  9  =  QR2
18  =  QR2
√
18
 =  QR
3
√
2
 =  QR

Now, we can proceed to the solution in several different ways. One way is to use the Pythagorean theorem:
  
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