过椭圆x2a2+y2b2=1上一点的切线方程为x0xa2+y0yb2=1y′=−b2xa2y,则斜率k=−b2x0a2y0切线方程y−y0=−b2x0a2y0(x−x0)带入x02a2+y02b2=1,则x0xa2+y0yb2=1 过椭圆\frac{x^2}{a^2}+\frac{y^2}{b^2}=1上一点的切线方程为\frac{x_0x}{a^2}+\frac{y_0y}{b^2}=1\\ y'=-\frac{b^2x}{a^2y},则斜率k=-\frac{b^2x_0}{a^2y_0}\\ 切线方程y-y_0=-\frac{b^2x_0}{a^2y_0}(x-x_0)\\ 带入\frac{x_0^2}{a^2}+\frac{y_0^2}{b^2}=1,则\frac{x_0x}{a^2}+\frac{y_0y}{b^2}=1 过椭圆a2x2+b2y2=1上一点的切线方程为a2x0x+b2y0y=1y′=−a2yb2x,则斜率k=−a2y0b2x0切线方程y−y0=−a2y0b2x0(x−x0)带入a2x02+b2y02=1,则a2x0x+b2y0y=1