Question

At any point of a curve (subtangent) $\times$ (subnormal) is equal to the square of the -

• A. slope of the tangent at that point
• B. slope of the normal at that point
• C. abscissa of that point
• D. ordinate of that point

Answer 1

The correct option is D ordinate of that point

We know, $\text{subnormal}=y\frac{dy}{dx}$
and $\text{subtangent}=\frac{y}{\frac{dy}{dx}}$
Therefore, $\text{subnormal}\times \text{subtangent}=y^2=$ square of ordinate at that point on the curve ${}^{\prime }{y}^{\prime }.$
Hence, option 'D' is correct.