The refractive index of diamond is 2.4175 and that of ethanol is 1.365 for the 589 nm light. What is the critical angle in degrees for a 589 nm beam when it travels from diamond to ethanol? Respond with the correct number of significant figures in scientific notation (Use E notation and only 1 digit before decimal e.g. 2.5E5 for 2.5 x 10)

The equation provided was this:

sinc=u2u1=n1n2