What is the length of a radius of the circle represented by the equation x2 + y2 - 4x - 4y + 4 = 0?

A) 2 units

B) 4 units

C) 8 units

D) 16 units

A) 2 units

Step-by-step explanation:

Given;

x² + y² - 4x - 4y + 4 = 0

Consider general circle equation;

(x - h)² + (y - k)² = r²

where;

(h , k ) is the center of the circle

r is the radius of the circle

x² + y² - 4x - 4y + 4 = 0

subtract 4 from both sides of the equation

x² + y² - 4x - 4y  =  - 4

square half of coefficient of x and y, and add them to both sides of the equation

x² +  - 4x + (-2)² +  y² - 4y + (-2)² = - 4 +  (-2)² +  (-2)²

factorize x and y

(x - 2)² + (y - 2)² = - 4 + 4 + 4

(x - 2)² + (y - 2)² = 4

(x - 2)² + (y - 2)² = 2²

Compare this final equation to general equation of a circle

(x - 2)² + (y - 2)² = 2²  

(x - h)² + (y - k)² = r²

r = 2

Thus, the length of a radius of the circle is 2 units

to plot points   for x just start at the origin (middle) and go to the left however many times it say(if the number is a positive) if the number is a negative then go right however many times it says if it is 0 go nowhere

now keep you pencil there and go up however many times it says on y(if it is positive) if it is negative then go down however many times it says. if it says 0 go nowhere.

you have just plotted a point! now when you finish plotting all of them connect them with a ruler

plot each point as (-3, 7), (0,4), (3,1), (8,-4)   in the parenthesis on the left of the comma is x and the right is y.