Help me i dont know Reflection and Refraction

Please help me with this

http://www.flickr.com/photos/79694554@N07/7317470038/

Light with a frequency of 5.5×1014 Hz is travelling through glass and strikes a glass/air interface as shown above. Angle X1 is 26.0o to the normal. Some of the light emerges from the glass and some is reflected back into the glass. If the index of refraction for this glass is 1.79, what is the value of angle X3?


And
What is the value of angle X2?

And

What is the speed of light in this glass?

And

What is the wavelength of this light in the glass?

Finally, what is the largest angle that the light in this glass could make with the normal and still produce an emergent ray into air?

sin(x3) / sin(x1) = n(glass)/n(air) = 1.79/1 (law of Snellius)
sinx(3) = sin(x1)*1.79
sinx3 = sin(26)*1.79
sinx3 = 0.7847
x3 = 51.69°
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x2 = 26° , as x1
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speed in air/speed in glass = 1.79/1
3*10^8 m/s / 1.79 = speed in glass = 1.676*10^8 m/s
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wavelength = c/f = 1.676*10^8/(5.5*10^14) = 3.04*10^-7 m
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x3 is 90° in the border case

sin(x1)/sin(x3) = 1/1.79
sinx1/1 = 1/1.79
sinx1 = 33.96° <--- maximum angle


OG