Question

cos1° + cos2° +
+ cos 179º =​

Answer 1

Step-by-step explanation:

cos1°+cos2°+cos3°................................+cos177°+cos178°+cos179°

=cos1°+cos2°+cos3°.....................cos89°+cos90°+cos91°....................cos177°+cos17°+8cos179°

=cos1°+cos2°+cos3°+...…..............cos89°+cos90°+cos(180-89)°+.. ............cos(180-3)°cos(180-2)°cos(180-1)°

=cos1°+cos2°+cos3°+…….........cos89°+cos90°-cos89°.................-cos3°-cos2°-cos1°

=cos1°-cos1°+cos2°-cos2°+...,.............+cos89°-cos89°+0. {cos90°=0)

=0+0+0+0.........+0=0