Light Beam calculations
Beam diameter = distance * (2 * tan(beam angle / 2))
Throw distance = Square root ((horizontal dist. * horizontal dist.) + (vertical dist. * vertical dist.))

Light output calculations
Lux = candela / distance in metres x distance in metres
Foot-candles = candela / distance in feet x distance in feet
Foot-candles = Lux / 10.8

Electrical calculations
Power = Voltage * current Watts = Volts * Amps
Current = Power / Voltage Amps = Watts / Volts
RMS Volts = 0.707 * Peak Volts RMS Volts = 1.11 * Average Volts