Calculating Angle of Deviation in a Prism

[allstar123]

light enters the side of an equilateral crown glass (1.62) prism at an angle of incidence of 35deg determin the angleof deviation after it has passed through the prism

i don't know what equation I am supposed to use

i got the angle of refraction into the glass that is 20.74deg but i don't know what I am supposed to do know please hepl

 

[allstar123]

am i just supposed to add up the angle of incidence withe angle of refraction

 

[Dadface]

am i just supposed to add up the angle of incidence withe angle of refraction

Hello allstar,to get you started sketch a ray diagram to show a ray entering,passing through and then emerging from the prism.The angle of deviation(D) is the angle between the incident and emergent rays.Extend two of the lines on your sketch to show D,the rest is geometry.