Saved Bookmarks
| 1. |
Prove that : Cos 20° + Cos 100° + Cos 140º = 0 |
|
Answer» Step-by-step EXPLANATION: cos20∘+cos100∘+cos140∘ =(cos20∘+cos140∘)+COS(90∘+10∘) =2cos80∘cos60∘−sin10∘=cos80∘−sin10∘ =sin10∘−sin10∘=0 |
|