From here show that K=5/2

Step 1: Identify the coordinates of point D, the maximum point of the curve.
The curve is given by $y = 2x(3-x) = 6x - 2x^2$.
To find the maximum point, we differentiate $y$ with respect to $x$ and set the derivative to zero.

$$\frac{dy}{dx} = 6 - 4x$$

Set $\frac{dy}{dx} = 0$:

$$6 - 4x = 0$$ $$4x = 6$$ $$x = \frac{6}{4} = \frac{3}{2}$$

Substitute $x = \frac{3}{2}$ back into the curve equation to find the y