Correct Answer - `(2sqrt(6)-1)/(2)`
For middle prism, `r+r=A`
`2r=60^(@)`
`rArr r=30^(@)`
Refraction from interface of `I^(st)` surface
`1 sin30^@=1.5 sintheta`
`1.5sin(60-theta)=musin30^(@)`
`rArr sintheta=1//3 and cos theta=sqrt(8)//3`
Refraction from interface of `I^(st)` & `II^(st)` prism,
`1.5sin60^(@) costheta-1.5cos60^(@)sintheta=musin30^(@)`
`(1.5)xx(sqrt(3))/(2)xx(2sqrt(2))/(3)-1.5xx(1)/(2)xx(1)/(3)=muxx(1)/(2)`
`sqrt((3)/(2))-(1)/(4)=mu(1)/(2)`
`rArr mu=sqrt(6)-(1)/(2)=(2sqrt(6)-1)/(2)=1.95` ltbr
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