SAT数学备考经典模拟题训练4

>>SAT数学模拟题：SAT数学备考经典模拟题训练4

>>SAT考试辅导

Read the following SAT test question and then click on a button to select your answer.

A circle in the xy-plane has its center at (-100,221) and a diameter of 17. Which of the following is an equation of the circle?

A.(x+100)^2+(y-221)^2=7

B.(x+100)^2+(y-221)^2=2

C.(x-100)^2+(y+221)^2=7

D.(x-100)^2+(y+221)^2=2

【答案解析】

答案：A

解析：

The formula for a circle with a center at (h,k) and a radius of r is: (x-h)^2+(y-k)^2=r^2

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=8.5^2

In standard form, the equation of this circle is: (x+100)^2+(y-221)^2=72.25

上面的模拟题都做完了吗大家，做题后也要对照解析认真总结自己的不足之处哦。更多SAT数学模拟题可登录坦途网SAT考试频道找到，祝大家考试顺利！