Question

Find the value of
(i)cosec (-1650)
(ii)cos (-9π/4)

Answer 1

(i) cosec (-1650) = -cosec (360(4)+210)
= -cosec 210°
= -cosec (180+30)
= (-cosec 30°)
= -(-2)
= 2

(ii) cos(-9π/4) = cos (9π/4)
= cos (2π + π/4)
= cos π/4
= cos 180/4
= cos 45°
= 1/√2

Answer 2

1)cosec(-1650)=2
2)cos(-9pie/4)=1/√2