Question

1. Which is the equation of a circle with center (–2, 3) and radius r = 5?
(x + 2)² + (y – 3)² = 10
(x + 2)² + (y – 3)² = 25
(x – 2)² + (y + 3)² = 10
(x – 2)² + (y + 3)² = 25

2. A circle with center (–1, 2) passes through point (2, –2). Which is true?

The radius is.
The diameter is 10.
The equation is (x + 1)² + (y – 2)² = 10.
The circumference is 25.
4. Which is the equation of a circle with diameterwith A(5, 4) and B(–1, –4)?
(x – 5)² + (y – 4)² = 10
(x + 5)² + (y + 4)² = 100
(x – 2)² + y² = 25
(x + 2)² + y² = 5

Answer 1

Hello,

1) (x+2)²+(y-3)²=5² Answer B 

2) center(-1,2) passing through (2,-2)

(x+1)²+(y-2)² =r²
if x=2 and y=-2 ==>(2+1)²+(-2-2)²=9+16=25

r=5

The radius is 5.
The diameter is 10.
The equation is (x + 1)² + (y – 2)² = 10. False 25
The circumference is 25. (false, 2pi*5=10pi)

4)
A(5, 4) and B(–1, –4) , M middle of AB is ((5+(-1))/2,(4+(-4))/2)=(2,0)

Radius is [MB|=√((2-(-1))²+(0+4)²)=√(9+16)=5

(x-2)+(y-0)²=5²
==>(x-2)²+y²=25

Answer C