Question

Sin 12×cos 18×sec 78×cosec72=?

Answer 1

sin 12=cos78(standard complimentary formula)
cos18=sin72
eqn:
cos78*sin72*sec78*cosec72.
we know, sec 78=1/cos78
cosec72=1/sin72
(cos78*sin72)/(cos78*sin72)
=1 answer.