How do you provle #cos (pi-x) =- cosx#?
1 Answer
Jan 30, 2016
see explanation
Explanation:
using the trig formula: cos(x-y) =cosxcosy + sinxsiny
hence
# cos (pi - x) = cospicosx + sinpisinx# now
# cospi = -1 , sinpi = 0 # then
# cos(pi - x ) = -1 cosx + 0 = -cosx #
