Q9
The equation of circle with centre (1, -2) and radius 4 cm is:
A.
x2 + y2 + 2x - 4y = 16
B.
x2 + y2 - 2x + 4y = 16
C.
x2 + y2 + 2x - 4y = 11
D.
x2 + y2 - 2x + 4y = 11
AnswerAnswer: Option D
Solution
Answer: Option D
Solution:
(x - a)2 + (y - b)2 = r2(x - 1)2 + [y - (-2)]2 = 42
x2 - 1 - 2x + y2 + 4 + 4y = 16
x2 + y2 - 2x + 4y = 11