What is the radius of the circle given by the equation below?

x2 + 12x + y2 - 12y = -56
A. 2
B. 16
C. 4
D. 8

C

Step-by-step explanation:

First, you gotta complete the square!

x^2+12x+36 = (x+6)^2

y^2-12y+36 = (y-6)^2

So, we have (x+12)^2 + (y-6)^2 = -56 + 36 + 36

The right side of the equation is the radius^2.

Simplify:

-56 + 36 + 36 = 16

The square root of 16 is 4, so the answer is C!

x = central angle apc = measure of minor arc ac

the two angles x and 30 add to 180, so x+30 = 180 and x = 180-30 = 150. the measure of minor arc ac is 150 degrees.

what we need to do from here is find the circumference and then multiply it by x/360 since there are 360 degrees in a circle. in this case, x = 150, so x/360 = 150/360 = 15/36 = 5/12. the shortest distance along the curve from a to c is 5/12 of the distance around the entire circle (aka circumference)

c = circumference

c = pi*d

c = pi*24

c = 24pi

now multiply this by 5/12 to get

distance along minor arc ac = (5/12)*(circumference)

distance along minor arc ac = (5/12)*(24pi)

distance along minor arc ac = 10pi

the formula you can use is

l = (x/360)*pi*d

with

l = length of minor arc

x = central angle

d = diameter

which essentially is the steps we took though a bit differently.

option: d is correct

step-by-step explanation: