Question

pls ans my question with reasons and steps

Answer 1

Snell's Law

$u = \frac{ \sin(i) }{ \sin(r) }$
for first surface ,
i = 75°, r = 60° ( alternate interior angle)

so,
$u = \frac{ \sin(75) }{ \sin(60) } \: \: \: ....(1)$
for second surface,
$u = \frac{ \sin(i) }{ \sin(30) } \: \: \: .....(2)$
using eqn (1) & (2),
$\sin(i) = \sin(30) \times \frac{ \sin(75) }{ \sin(60) } \\ = \frac{ 1 }{2} \times \frac{ \sin(75) }{ \frac{ \sqrt{3} }{2} } \\ = \frac{ \sin(75) }{ \sqrt{3} }$


hope, it helped..