The degree of the differential equation $\frac{\mathrm{d}^2 y}{\mathrm{~d} x^2}+3\left(\frac{\mathrm{~d} y}{\mathrm{~d} x}\right)^2=x^2 \log \left(\frac{\mathrm{~d}^2 y}{\mathrm{~d} x^2}\right)$ is

If the sum of the squares of the distances of a point $\mathrm{P}(x, y, z)$ from the three co-ordinate axes is 324 , then the distance of point P from the origin is ….

For a real number $x,[x]$ denotes the greatest integer less than or equal to $x$. Then the value of

$$ \begin{array}{r} {\left[\frac{1}{2}\right]+\left[\frac{1}{2}+\frac{1}{100}\right]+\left[\frac{1}{2}+\frac{2}{100}\right]+\left[\frac{1}{2}+\frac{3}{100}\right]+} \left[\frac{1}{2}+\frac{99}{100}\right]= \end{array} $$

The angle between the lines $3 x=2 y=-\mathrm{z}$ and $-x=6 y=-4 z$ is