Question

A ray of light passes from vacuum into a glass of refractive index of 1.5 the angle of incidence found to be twice the angle of refraction what is angle of incidence

Answer 1

$1.5 = \sin(x ) \div \sin(2x)$
$1.5 = \sin(x) \div 2 \sin(x) \cos(x)$
$1.5 = 1 \div2 \cos(x)$
$3 = 1 \div \cos(x)$
$3 = \sec(x)$