Projectile motion max height problem

[dmb325]

Homework Statement

A projectile is launched from ground level with an initial speed of 48.7 m/s. Find the launch angle (the angle the initial velocity vector is above the horizontal) such that the maximum height of the projectile is equal to its horizontal range. (Ignore any effects due to air resistance.)

Homework Equations

Vocos(angle)=Vx
Vosin(angle)=Vy

The Attempt at a Solution

(X, 0) and (X/2, Ymax)

 

[Delphi51]

In my experience you can always solve these projectile motion questions with the high school method. Write x = vt for the horizontal part,
Vy = Viy + at AND y = Viy*t - ½at² for the vertical part.
In this problem you need all three equations because you have unknown t, Vi and the angle. Give it a try!