Question

1. Find the value of
(i) cos 840°
(ii) sin 870° (iii) tan (-120°)
(iv) sec (-420) (v) cosec (-690°) (vi) tan (225)
(vii) cot (-315°) (viii) sin (-1230°) (ix) cos(4959​

Answer 1

Answer:

1)cos840

=>cos[360+480]

=cos[480]

=cos[360+120&

=cos[120]

=cos [90+30]

= -sin30

= -1\2