Find the center of the circle x² + y² - 6x - 8y + 9 = 0.
A
(3, 4)
B
(–3, –4)
C
(3, –4)
D
(–3, 4)
Analysis & Theory
g = –3, f = –4 ⇒ center = (–g, –f) = (3, 4).
Find the radius of the circle x² + y² - 6x - 8y + 9 = 0.
A
√36
B
√25
C
√16
D
√13
Analysis & Theory
Radius = √(g² + f² - c) = √(9 + 16 - 9) = √16 = 4.
The circle x² + y² + 4x + 2y - 11 = 0 has center?
A
(–2, –1)
B
(2, 1)
C
(–4, –2)
D
(4, 2)
Analysis & Theory
g = 2, f = 1 ⇒ center = (–g, –f) = (–2, –1).
The circle x² + y² + 4x + 2y - 11 = 0 has radius?
A
3
B
4
C
5
D
√29
Analysis & Theory
Radius = √(g² + f² - c) = √(4 + 1 - (–11)) = √16 = 4.
Find center of circle x² + y² - 10x + 6y + 18 = 0.
A
(5, –3)
B
(–5, 3)
C
(10, –6)
D
(–10, 6)
Analysis & Theory
g = –5, f = 3 ⇒ center = (–g, –f) = (5, –3).
Find radius of circle x² + y² - 10x + 6y + 18 = 0.
A
4
B
5
C
6
D
7
Analysis & Theory
Radius = √(25 + 9 - 18) = √16 = 4.
Find the center of circle x² + y² + 2x - 4y - 20 = 0.
A
(–1, 2)
B
(1, –2)
C
(–2, 1)
D
(2, –1)
Analysis & Theory
g = 1, f = –2 ⇒ center = (–g, –f) = (–1, 2).
Find the radius of circle x² + y² + 2x - 4y - 20 = 0.
A
5
B
6
C
7
D
√25
Analysis & Theory
Radius = √(1 + 4 - (–20)) = √25 = 5.
The circle x² + y² - 8x - 6y + 20 = 0 has center?
A
(4, 3)
B
(–4, –3)
C
(8, 6)
D
(–8, –6)
Analysis & Theory
g = –4, f = –3 ⇒ center = (–g, –f) = (4, 3).
The circle x² + y² - 8x - 6y + 20 = 0 has radius?
A
√5
B
3
C
4
D
√7
Analysis & Theory
Radius = √(16 + 9 - 20) = √5.