抛物线的焦点弦公式总结

鹤壁高中蔡凤敏2016.11.04抛物线的焦点弦公式总结2122xPBFxpAFpxy22pxy2-221-2-2xPBFxpAFcos1cos1pBFpAFcos-1cos1pBFpAFPBFAF211.),,(),,(2211的倾斜角是直线的一条弦，设是抛物线过焦点已知AByxByxAFAB焦半径公式1相同2122yPBFypAFsin1sin1pBFpAFsin-1sin1pBFpAFPBFAF21121-2-2yPBFypAF焦半径公式1pyx22相同pyx2-2)(21xxpABpxy22pxy2-22sin2pAB)(-21xxpAB2sin2pAB)11(22kpAB)11(22kpAB相同焦点弦公式2pyx2-2)(21yypAB2cos2pAB)(-21yypAB2cos2pAB)1(22kpAB)1(22kpAB相同pyx22焦点弦公式22212214pyypxxpxy22pxy2-2相同A,B两点的横坐标之积、纵坐标之积32212214pyypxxpyx2-24221221pyypxx相同4221221pyypxxpyx22A,B两点的横坐标之积、纵坐标之积3pxy22pxy2-24三角形OAB的面积sin22PSOAB相同sin22PSOABpyx22pyx2-2cos22PSOAB相同cos22PSOAB4三角形OAB的面积鹤壁高中欢迎您！再见！