Two projectiles are thrown with same initial velocity making an...

Let projection speed is $u$, The formula for the range of the projectile is given by, $R = \dfrac{{u}^{2}\sin 2\theta}{g}$. Therefore,

${R}_{1} = \dfrac{{u}^{2}\sin \left(90 °\right)}{g}; {R}_{2} = \dfrac{{u}^{2}\sin \left(60 °\right)}{g}$

$\dfrac{{R}_{1}}{{R}_{2}} = \dfrac{\sin 90 °}{\sin 60 °} = \dfrac{2}{\sqrt{3}}$