Question

The centre of a circle is (-1, 2). If the radius of the circle is 4 cm, then what will be the equation of circle?

Answer 1

Answer:

eq of the circle is (x-x1)^2+ (y-y1)^2= r^2

Step-by-step explanation:

(x+1)(x+1)+(y-2)(y-2)=16

x^2+2x+1+y^2-4y+4=16

x^2+y^2+2x-4y=11

Answer 2

Answer:

The equation of the circle is x² + y² + 2x - 4y - 11 = 0.

Step-by-step explanation:

The general form of a circle is:

$(x-h)^{2}+(y-k)^{2}=r^{2}$

Here (h, k) is the center of the circle.

Given:

(h, k) = (-1, 2)

r = 4 cm

Compute the equation of he circle as follows:

$(x-h)^{2}+(y-k)^{2}=r^{2}\\(x-(-1))^{2}+(y-(2))^{2}=4^{2}\\(x+1)^{2}+(y-2)^{2}=16\\x^{2}+1+2x+y^{2}+4-4y=16\\x^{2}+y^{2}+2x-4y-11=0$

Thus, the equation of the circle is x² + y² + 2x - 4y - 11 = 0.