At any point of a curve (subtangent) × (subnormal) is equal to the square of the |
slope of the tangent at that point slope of the normal at that point abscissa of that point square of ordinate of that point |
square of ordinate of that point |
We have, Sub normal = $y \frac{d y}{d x}$, Sub tangent = $\frac{y}{\frac{d y}{d x}}$ ∴ Sub normal × Sub tangent = $y^2$ |