Galileo writes that for angles of projection of a projectile at angles (45 + θ) and (45 - θ), the horizontal ranges described by the projectile are in the ratio of (if θ < 45)
1 : 1
For angle (45o−θ),R=u2sin(90o–2θ)g=u2cos2θg
For angle (45o+θ),R=u2sin(90o+2θ)g=u2cos2θg