Use the following four coordinates to determine which one has a distance of 10 units from point C (1, 2).
(3, 4)
(7, 1O)
(6, 7)
(8, 9)
consider the equation of the circle with centre (1,2) and radius 10
Its equation is
(x-1)^2 + (y-2)^2 = 100
(7, 10) satisfies that equation,
(7-1)^2 + (10-2)^2 = 100
6^2 + 8^2 = 100
36+64 = 100
100=100
so it is (7,10)