Hello.
The find the measure of side c, you should use the Law of Sines. This law states, sin A / a = sin B / b = sin C / c. Since you are given two angle measures and the measure of a side, you can substitute these values into sin B / b = sin C / c.
Here are the given values: sin B = 105 degrees, sin C = 15 degrees, side b = 2 cm.
sin (105) / 2 = sin (15) / c (multiply both sides by c)
sin (105) / 2 · c = sin (15)
0.48296... · c = 0.25881... (divide both sides by 0.48296)
c = 0.53588..
The value of side c is about 0.5 centimeters.