Triangle ABC has vertices A=(0, 1), B=(1, 0) and C=(0, 0) in the coordinate plane.

The insides of the sides are lined with mirrors, and then a laser beam is fired from the origin with a slope of 314/379

Which corner of the triangle will the laser beam hit first?

I am not sure of this: I didn't do a simulation (yet), but I think it will hit C, the origin, first.

Since arctan(314/379) is 39.6 deg, when the beam hits AB at "I" it

makes a triangle CIB with angle I = 95.3 deg. = 180-45-39.6.

This sends the beam down to "J" near the middle of CB.

Angle IJB = 180-95.3 - 45 = 39.7 deg. Then, my crude sketch

has the beam zig-zagging its way into C.

*Edited on ***February 20, 2019, 1:25 am**