Question

If secθ.sinθ=0 then find the value of θ

Answer 1

$n(\pi \div 2)$

Answer 2

as the product if two positive quantities is zero so one of them must be zero and multiplying anything with zero gives product is zero.
Then either sec○ or sin○ is zero.
if sin theta is 0 then theta is 0. (equation i)
if sec theta is 0 then there is no solution. (equation ii)
so theta must be zero from equation i.