Please check my math re beam spread from CR6?
The final number comes out so large, that I have to imagine that I did something wrong in this calculation.
The specs on the Cree CR6 say is has an approximately 80 degree beam angle. My ceilings are going to be 9 feet tall.
I'm trying to get an idea of the distance of the light spread on the floor.
The geometry formula looks to me like the radius of the light circle on the floor (R) is equal to the tangent of half the beam angle (tan 40) times the ceiling height (9 feet). (Because if I recall my high school geometry correctly, the tangent of the angle is the opposite side over the near side).
If I plug in the numbers, I get tan 40 = 0.839 times 9 feet = 7.55 feet (!)
Which would indicate a light circle on the floor of 15 feet in diameter (twice the 7.55 feet), which seems awfully huge.
Any mistakes in my math? Or set up of the geometry?