tried figuring this out but I keep getting confused. If someone can explain ? thank you

jjennylove Oct 4, 2019

#1**+2 **

The first isn't too difficult

We have the form (x - h)^2 + (y - h)^2 = r^2

The center is ( x , h) and the radius = sqrt (r^2) = r

So....we have

(x - 2)^2 + (y + 3)^2 = 80 writing this in a slightly different form we have

(x - 2)^2 + ( y - (-3) )^2 = 80

So.....the center is (2, -3) and the radius = sqrt (80) = sqrt (16 *5) = 4sqrt (5)

CPhill Oct 4, 2019

#2**+3 **

The second one requires a little thinking

If the center of the circle lies on the line y = 6x + 2 and the circle is tangent to the x axis at (-2, 0) then the the x coordinate of the center of the circle is at x = -2

So.....the y cordinate of the center must be y = 6(-2) + 2 = -10

So....the center is ( -2, -10)

And since this circle is tangent to the x axis......the radius must = 10

So.....the equation is (x + 2)^2 + (y + 10)^2 = 100

See the graph here : https://www.desmos.com/calculator/8abh7hhozi

CPhill Oct 4, 2019

#4**+1 **

Was a bit confusing but I get how you got the answer, desmos helped my understand it more as well. Thanks

jjennylove
Oct 4, 2019