A fighter jet is flying horizontally at a certain altitude with a speed of \( 200 \, \text{ms}^{-1} \). When it passes directly overhead an anti-aircraft gun, a bullet is fired from the gun, at an angle \( \theta \) with the horizontal, to hit the jet. If the bullet speed is \( 400 \, \text{m/s} \), the value of \( \theta \) will be ____________\( ^\circ \).