Find the direction of the sum of these two vectors: 5.00m,30.0,60.0m

  -93.7° . . .  or  . . . 266.3° (measured CCW from the +x axis)

Explanation:

The attached screen shot of a calculator's output shows the answer to this problem along with several other of your vector sum problems.

Of course, any negative angle can be converted to the corresponding positive angle by adding 360°.

All of the inputs and outputs are of the form ...

  magnitude∠direction

where the direction is the angle measured counterclockwise from the +x axis. (Some of your problems, like this one, use a different angle reference, so the angles need to be converted.)

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

snell's law

refractve index = sin incidence / sin refraction