Two objects are projected with same velocity u however at different angles α and β with the…

Given: $\alpha +\beta =90°$

Range of the first projectile:

$R_1=\frac{u^2\sin 2\alpha }{g}$

Range of the second projectile:

$$\begin{gathered} R_2=\frac{u^2\sin 2\beta }{g} \\ =\frac{u^2\sin (180°-2\alpha )}{g} \\ =\frac{u^2\sin 2\alpha }{g} \end{gathered}$$

As we can see, both are equal.

$R_1=R_2$

Therefore,

$R_1:R_2=1:1$