E = cos20º + cos40º + cos60º + … cos160º + cos180º a) 0 b) 1 c) -1
d) 2 e) -2

brainliest to the most elaborated answer

sorry man but i have a doubt please help

for meeting purpose

which app do u use

C) – 1

Step-by-step explanation:

E = cos20º + cos40º + cos60º +cos80° + cos 100°+cos120° +cos140° +cos160º + cos180º

E= 0.9 + 0.76 + 0.5+0.17+(-0.17)+(-0.5)+(-0.76) + ( – 0.9 ) + (– 1 )

E= 0.9 + 0.76 + 0.5 +0.17 - 0.17 - 0.5 -0.76 – 0.9 – 1

E= – 1

So ; equal – 1

I hope I helped you^_^