Question

angle of deviation in detail?

Answer 1

here if a angle incident. "i" on mirror and reflects in a path "r" then
the angle between the extended incident ray and reflected ray isangle of deviation
hereα+i+r+d+i =270
3i +d+α=270
i=r
and α+i=π/2
α= π/2-i
3i +d +(π/2-i)=270
d=270-π/2+i-3i
d=180-2i


sub 90 =i+α
i=90-α
d=180-2(90-α)
d=180-180+2α
d=2α