How do you find the circumference and area of the circle whose equation is x^2+y^2=36x2+y2=36?

1 Answer
Sudip Sinha
Jan 27, 2016

Circumference = 12 pi 12π.
Area = 36 pi 36π.

Explanation:

The equation of a circle centred in the origin having radius r is x^2 + y^2 = r^2 x2+y2=r2. Comparing with the equation of the given circle, we get r^2 = 36 => r = 6 r2=36⇒r=6. (Since r > 0 r>0.)

Note that all we need to calculate the area and circumference of a circle is the radius. Now we can use the formulae known to calculate the required values.

Circumference = 2 pi r = 2 pi * 6 = 12 pi 2πr=2π⋅6=12π.
Area = pi r^2 = 36 pi πr2=36π.

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