NAME________________________________________DATE_______________________
ALGEBRA2
CONIC SECTIONS
MRS. BINASO
CIRCLES
Given the following centers and radii, write an equation for each circle.
1. (-3,5); r = 4
2. (2,6); r = 1
3. (0,-8); r = 9
4. (-1,-3); r = 7
5. (5,0); r = 2
Identify the center and radius of each circle. Then graph each circle.
6. (x – 2)2 + (y – 3)2 = 36
7. (x + 5)2 + (y + 8)2 = 25 8. (x – 1)2 + (y + 7)2 = 16
9. x2 + (y – 3)2 = 4
10. 4x2 + 4y2 = 36
11. (Text p472) A tree in your garden has a ring of flowers. Each flower is four feet from the
center of the tree trunk. You draw a coordinate grid to model your yard. The tree trunk
is located at (-4,3). Write an equation that models the ring of flowers.
12. (wkbk p175 #3) Which of the following points is not on the circle (x – 4)2 + (y – 3)2 = 25?
(1) (8,6)
(2) (-1,3)
(3) (0,0)
(4) (-4,-3)
13. (wkbk p175 #4) Jen is playing with a Frisbee whose diameter is 12 inches. If she tosses
it onto a coordinate plane, and its center falls on the point (-2,1), what is the equation of
the Frisbee?
(1) x2 + y2 = 36
(3) (x + 2)2 + (y – 1)2 = 36
2
2
(2) (x – 2) + (y – 1) = 36
(4) (x – 2)2 + (y + 1)2 = 36
14. (wkbk p175 #9) Harmony and Melodie were blowing bubbles when one of them landed
on Derek’s math homework and burst on the graph paper. The bubble formed a perfect
circle on the coordinate grid with a center at (6,-5) and a radius of 4.5. Which of the
following represents the equation of the bubble’s circle?
(1) 4.52 = (x – 6)2 + (y + 5)2
(3) (x + 6)2 + (y – 5)2 = 20.25
2
2
2
(2) x + y = 4.5
(4) (x – 6)2 – (y + 5)2 = 20.25
15. (wkbk p176 #10) Someone left a hot coffee mug on Mrs. Hilton’s coffee table and it
stained the table. Unfortunately, no one will admit guilt. Mrs. Hilton decides to find the
diameter of the mug so she can determine whose mug created the stain. If the equation of
the circle left by the coffee mug is (x – 1)2 + (y + 4)2 = 7.84, what is the diameter of the
mug?
(1) 7.84
(2) 5.6
(3) 2.8
(4) 1.4