A unit vector parallel to the resultant of vectors $\overrightarrow{A}=4\hat{\mathrm{i}}-3\hat{\mathrm{j}}$ and $\overrightarrow{B}=8\hat{\mathrm{i}}+8\hat{\mathrm{j}}$ will be

If a vector $\overrightarrow{P}$ is making the angles $\mathrm{\alpha }, \mathrm{\beta }$ and $\mathrm{\gamma }$, respectively, with $X, Y$ and $Z$ axes, then ${\sin }^2\mathrm{\alpha }+{\sin }^2\mathrm{\beta }+{\sin }^2\mathrm{\gamma }=$