how do I solve questions like cos1+cos2+cos3+....cos359Please help.

Dear Nikhil,

Answer is -1,(knowing the cos x graph will help in such problems) cos 1 gets cancelled with cos 179 as cos 179=-cos 1 and cos 2 with cos 178 and so on so all the terms from cos 1 to cos 179 vanish the same happens again from cos 181 onwards as cos 181=-cos 359 so all the terms from cos 181 to cos 359 also get cancelled the left over term is cos 180 =-1, Like my answer if you have understood the solution

Regards

Noaman Ali