Half of maximum possible projectile range

[kerbyjonsonjr]

Homework Statement

A projectile's horizontal range on level ground is R=v₀²sin2$$\vartheta$$/g. At what launch angle or angles will the projectile land at half of its maximum possible range

Homework Equations

The Attempt at a Solution

All I know is that a projectile goes the furthest when the angel is 45^o. I know I have to say 1/2R = the whole thing but I am not sure what to do to solve this. There are two answers. Thanks for any help! I appreciate it.

 

[gneill]

Look at your formula for the range. What's special about 45° ?

 

[kerbyjonsonjr]

Look at your formula for the range. What's special about 45° ?

It makes sin2x equal to 1. I GOT IT! I want the value where sin2x=.5 and that's at 15 and 75. Thank you!