【官方】SAT数学每日一题附答案和解析(2018年1月24日)
- 2018年01月24日13:14 来源：小站整理
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Math: Calculator Permitted
Read the following question and then select the best answer.
A circle in the x y-plane has its center at (-100,221)and a diameter of 17. Which of the following is an equation of the circle?
Select an Answer
Answer
A
(x+100)2+(y-221)2=72.25
Answer
B
(x+100)2+(y-221)2=289
Answer
C
(x-100)2+(y+221)2=72.25
Answer
D
(x-100)2+(y+221)2=289
答案及解析：
A
EXPLANATION
The formula for a circle with a center at(h,k) and a radius of r is:
(x-h)2+(y-k)2=r2
The length of the radius is half of the length of the diameter.
1/2×17=8.5
Using the coordinates of the center and the length of the radius of this circle in the equation yields:
(x- (-100))2+(y-221)2=8
In standard form, the equation of this circle is:
(x+100)2+(y-221)2=72.25
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