抛物线的焦点弦公式总结

鹤壁高中蔡凤敏2016.11.042122xPBFxpAF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AByxByxAFAB12122yPBFypAFsin1sin1pBFpAFsin-1sin1pBFpAFPBFAF21121-2-2yPBFypAF1pyx22pyx2-2)(21xxpABpxy22pxy2-22sin2pAB)(-21xxpAB2sin2pAB)11(22kpAB)11(22kpAB2pyx2-2)(21yypAB2cos2pAB)(-21yypAB2cos2pAB)1(22kpAB)1(22kpABpyx2222212214pyypxxpxy22pxy2-232212214pyypxxpyx2-24221221pyypxx4221221pyypxxpyx223pxy22pxy2-24sin22PSOABsin22PSOABpyx22pyx2-2cos22PSOABcos22PSOAB4