Question

Find the equation of the circle whose centre is in the first quadrant and radius 4

Answer 1

We know that the equation of a circle with center (h,k) and radius r units is (x−h)²+(y−k)²=r² .

or, acc to the question, centre is in the first quadrant and radius 4. That means h = k = 4 units. i.e. (4,4) Since it's the first quadrant the centre will be (h,k)

Therefore, equation will be:

(x−4)²+(y−4)²=4²

or, (x−4)²+(y−4)² = 16 [Ans]