Question 668482
Simplify each expresion:
Sin(-x)cot(-x)
=sin(-x)*cos(-x)/sin(-x)
=cos(-x)
..
sin(x)/cos(-x) + sin(-x)/cos(x)
=sin(x)/cos(x)-sin(x)/cos(x)
=0
..
cos(x) + cos(-x)
=cos(x) + cos(x)
=2cos(x)