如图在平面直角坐标系中,坐标原点O,A点坐标为(4,0),B点坐标(-1,0...答:(1)已知A(4,0),B(-1,0),则中点P=P(1.5,0)以AB为直径,则圆的半径为PC=AB/2=2.5 ∴圆方程为 (x-1.5)^2+y^2=2.5^2 令x=0,可解得C点坐标为C(0,2) (依图示负根舍弃)设过A,B,C的抛物线方程为y=ax^2+bx+c 带入三点坐标,可得 16a+4b+c=0 a-b+c=0 c=...
如图在平面直角坐标系中,坐标原点O,A点坐标为(4,0),B点坐标(-1,0...答:① 圆心P(3/2, 0), 半径r = 5/2 圆方程: (x - 3/2)² + y² = (5/2)²取x = 0, y = ±2 C(0, 2)显然过A、B、C三点抛物线可以表达为: f(x) = a(x+1)(x-4)f(0) = -4a = 2, a = -1/2 f(x) = -(x+1)(x-4)/2 ② 抛物线的对称...