The end points of the diameter of a circle are (1, -2) and (5, 16). Write the equation of the circle in standard form.

Answer 1

Find the distance between the two points and divide by 2. This will be the radius of the circle. D²=((5-1)²+(16+2)²)=340. The radius squared will be 340/4=85. The center will be at x=h=(5-1)/2+1=3 and y=k=(16+2)/2-2=7. The standard form is (x-h)2+(y-k)2=r2 thus the equation will be (x-3)²+(y-7)²=85.