The standard form of the equation of a circle is (x-h)^2 + (y-k)^2 = r^2, where (h,k) is the center of the circle, (x,y) is a point of the circle, and r is the length of the radius of the circle. When the equation of a circle is written, h,k, and r are numbers, while x and y are still variables. (x-2)^2 + (y-k)^2 = 16 is an example of a circle. The problem gives us two of the three things that a circle has, a point (5,9) and the center (-2,3). We need to find the radius in order to write the equation. We substitute -2 for h, 3 for k, 5 for x, and 9 for y to get (5 - (-2))^2 + (9 - 3)^2 = r^2 We simplify: 49 + 36 = r^2, r^2 = 85. We only need to know r^2 because the equation of a circle has r^2. We now have all the information to write the equation of a circle. (x + 2)^2 + (y - 3)^2 = 85.
Answer:
Step-by-step explanation:
the formula of a circle is
knowing the values of h, k, and r we can substitute them into the formula
knowing the
Answer: The correct option is (A). 3.
Step-by-step explanation: We are given to find the scale factor of dilation from ΔABC to ΔDEF.
As shown in the figure, the lengths of the sides of ΔABC to ΔDEF are
AB = 5 units, BC = 4 units, CA = 3 units,
DE = 15 units, EF = 12 units, FD = 9 units.
We know that the scale factor is given by
Therefore, the scale factor of dilation from from ΔABC to ΔDEF is
Thus, the required scale factor is 3.
Option (A) is correct.
