Lösung 4.1:5b
Aus Online Mathematik Brückenkurs 1
If the circle is to contain the point (-1,1), then that point's distance away from the centre (2,-1) must equal the circle's radius, r. Thus, we can obtain the circle's radius by calculating the distance between (-1,1) and (2,-1) using the distance formula,
When we know the circle's centre and its radius, we can write the equation of the circle,
which the same as
Note: A circle having its centre at (a,b) and radius r has the equation
