Solve Velocity Equation: -g(horizontal distance)/sin(2theta)

[LT72884]

So i was googling the mighty google for a general question on velocity and i happened upon this equation with no description of it. Only states it is a velocity equation

velocity=sqrt((-g)(horizontal distance)/sin(2theta))

sorry, symbols is not working on me laptop at the moment

Its been a LONG while since physics for me but i do not recal this equation.

an example was given of:
distance a ball was thrown = 290 feet
g= -32
angle ball was thrown was 26* ( i assume horizontal is 0* but sin 0 = o which can't have in denominator so something seems odd)

they end up with roughly 108.52 ft/sec

this eq seems strange to me. i threw a ball at roughly 8* and it took 1.002 seconds to go 15feet. if i plug that into me equation i get 42 feet/s

that doesn't sound right to me because after 1.002 seconds, the ball landed at 15 feet, so it can't be going 42 feet/sec then.

ANYWAY my MAIN QUESTION IS... WHAT EQUATION IS THIS HAHAHA

thanks

 

[fresh_42]

https://en.wikipedia.org/wiki/Projectile_motion#Maximum_distance_of_projectile