Find the equation of the chord of the circle x2+y2=25x^2 + y^2 = 25x2+y2=25 whose midpoint is (1,2)(1, 2)(1,2).
x+2y=5x + 2y = 5x+2y=5
x+2y=10x + 2y = 10x+2y=10
2x+y=52x + y = 52x+y=5
2x+y=42x + y = 42x+y=4