If a normal of curve `x^(2//3)+y^(2//3)=a^(2//3)` makes an angle `phi` from `X`-axis then show that its equation is `y cos phi -x sin phi = a cos 2phi` .

Explanation

To solve the problem, we need to show that the equation of the normal to the curve \( x^{2/3} + y^{2/3} = a^{2/3} \) that makes an angle \( \phi \) with the x-axis is given by:

\[ y \cos \phi - x \sin \phi = a \cos 2\phi \]

### Step-by-Step Solution:

...