If the coordinates of the endpoints of a diameter of a circle are.............

Question

If the coordinates of the endpoints of a diameter of a circle are (-2,-1) and (2,3) , how long is the radius of

the circle?

Answer 1

Diameter is the distance between the points

 

Diameter=(4² +4²)^1/2=4*2^1/2

 

So radius =2*2^1/2

 

Centre=(0,1)

Answer 2

The diameter d is the distance between the 2 endpoints, and the radius r is half of the diameter.

 

d = √[(-2-2)² + (-1-3)²] = √(16 + 16) = √32 = √(4*4*2) = 4√2

 

r = d/2 = (4√2)/2 = 2√2