Answer:

r =5*12' (5 degree 36 mins)

Explanation:

R.I =2.246

u =2.246

ip =tan-1 (u)

ip =tan-1 (2.246)

ip = 12*42'

u = sin ip  / sin r

2.246 =sin (12*42') / sin r

2.246 =0.2198 / sinr

sinr = 0.2198 /2.246

r =sin-1 (0.09786)

r = 5*36' (5 degree 36 mins)