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The Circle

QuestionAnswer
What is the standard form equation for circles? (x-h)^2 + (y-k)^2 = r^2
What do the variables h & k in the standard form represent? The variables h & k represent the location of the center of the circle.
What does the variable r in the standard form represent? The variable r represents the radius of the circle.
Where is the center, and what is the radius, of the following circle? x^2 + y^2 = 49 Since no h or k values are given, the center is at (0,0). Also, because r^2 = 49, r must equal 7.
Where is the center, and what is the radius, of the following circle? (x - 3)^2 + y^2 = 16 The h value is 3, and since no k value is given, the center is at (3,0). Also, because r^2 = 16, r=4.
Where is the center, and what is the radius, of the following circle? (x-4)^2 + (y-4)^2 = 25 Both the h and k values = 4. So, the location of the center is (4,4). Also, because r^2 = 25, r=5.
Where is the center, and what is the radius, of the following circle? (x+1)^2 + (y+3)^2 = 5 The h value is -1, and the k value is -3, so (-1,-3). Also, because r^2 = 5, r=āˆš 5.
Where is the center, and what is the radius, of the following circle? (x +2)^2 + (y-8)^2 = 4 The h value is -2, and the k value is 8, so (-2,8). Also, because r^2 = 4, r=2.
Where is the center, and what is the radius, of the following circle? (x -12)^2 + (y-2)^2 = 121 The h value is 12, and the k value is 2, so (12,2). Also, because r^2 =121, r=11.
Where is the center, and what is the radius, of the following circle? (x +11)^2 + (y-43)^2 = 32 The h value is -11, and the k value is 43, so (-11,43). Also, because r^2 = 32, r=āˆš 32.
Created by: philipcscott
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