[math]\Theta = \frac{m_ec^2}{E_{beam}} = \frac{0.511\ MeV}{44\ MeV} = 0.67\ ^o[/math]
[math]\Delta = 285.75cm\ *\ \tan(0.67^o) = 3.34cm[/math]
1) [math]\Delta = 3.34 cm \ \ \longarrow \tan^{-1}\left(\frac{m_ec^2}{E_{beam}}\right) = \frac{0.511\ MeV}{44\ MeV} = 0.67\ ^o[/math]