Question

Evaluate sin18 degree by cos 72 degree

Answer 1

SIN 18 / COS 72

==> SIN 18 / COS(90-18)

==> SIN 18 / SIN 18

==> 1

I HOPE ITS HELPFUL

Answer 2

sin18 degree =cos72 degree=
$\sqrt{5 - 1 \div 4}$