A sample is bombarded by incident $x-$rays, and free electrons in the sample scatter some of the $x-$rays at an angle of $=121\mathrm{.}0$ with respect to the incident $x-$rays, as shown in the drawing. The scattered $x-$rays have a momentum whose magnitude is $1\mathrm{.}946{10}^{-24}kg*\frac{m}{s}.$ Determine the wavelength $($in nm $)$ of the incident X$-$rays. $($For accuracy, use $h=6\mathrm{.}626{10}^{-34}J*s,c=2\mathrm{.}998{10}^8\frac{m}{s},$ and $m=9\mathrm{.}109{10}^{-31}kg$ for the mass of an electron.$)$

Number

Units