Question

A circle has equation x2+ y2-10x + 2y-20=0 the radius of circle is

Answer 1

Answer:

6.78 unit

Step-by-step explanation:

According to the given question,

Equation of the circle is,

x^2 + y^2 -10x + 2y - 20 = 0

Comparing this equation with the general form, we get

x^2 + y^2 + 2gx + 2fy + c = 0

Thus,

• 2gx = -10x

• 2g = -10

• g = -5

Similarly,

• 2fy = 2y

• 2f = 2

• f = 1

And c = -20

Therefore, g = -5, f = 1 and c = -20

We know,

Radius of circle ,R = √(g^2 + f^2 - c)

Radius of the circle is the distance between the centre of the circle to the any point on outer boundary of the circle.

Putting the values we get,

• R = √(25+1+20)

• R = √(46)

• R = 6.78 unit

Thus radius of the circle whose equation is x^2 + y^2 -10x + 2y - 20 = 0; is 6.78 unit.