Question

The equation x squared + y squared = r squared
find the equation of the circle with centre (0,0) and which contains the point (5,-2)

Answer 1

$(5-0)^2+(-2+0)^2=r^2\\ 25+4=r^2\\ 29=r^2\\\\ \boxed{x^2+y^2=\sqrt{29}}$