1. The equation of a circle is x²+y²+14x+10y-7=0. You must show all work. If you use DESMOS, you must put the snip of your work.

a. Fill in the blanks: x²+14x+___+y²+10y+___=___

b. What is the equation in Standard Form?

c. What is the center and radius of the circle?

2.

The equation of a circle is (x−11) ²+(y+15) ²=144.

(a) Johnny said that the center of the circle is located at (15, -11). Is Johnny correct? Explain your answer.

(b) Joyce said that the diameter of the circle is 144 units. Is Joyce correct? Explain your answer.

lordhelix Mar 23, 2019

#1**+1 **

We are completing the square on x and y

Take 1/2 of 14 = 7, square it =49 add to both sides

Take 1/2 of 10 =5, square it = 25 add to both sides

a. Fill in the blanks: x²+14x+ __49__+y²+10y+ __25__ = __74__

b. Standard Form = ( x + 7)^2 + ( y + 5)^2 = 74

c. Center ( - 7, - 5)

Radius = sqrt (74)

2.

The equation of a circle is (x −11) ²+(y+15) ²=144.

(a) Johnny said that the center of the circle is located at (15, -11). Is Johnny correct? Explain your answer.

In the form ( x - a)^2 + ( y + b)^2 = r^2....the center is ( a, - b).....so....

The center is (11, - 15)

(b) Joyce said that the diameter of the circle is 144 units. Is Joyce correct? Explain your answer.

144 = radius^2

12 = radius

2 * radius = diameter

2 * 12 =

24 = the diameter

CPhill Mar 23, 2019