Saved Bookmarks
| 1. |
सिद्ध कीजिए कि `cos alpha+cos beta+cos gamma +cos (alpha+beta+gamma)=4cos((alpha+beta)/(2))cos((beta+gamma)/(2))cos((gamma+alpha)/(2))` |
|
Answer» बायाँ पक्ष `=cos alpha+cos beta+cos gamma +cos(alpha+beta+gamma)` `=(cos alpha + cos beta)+[cos (alpha+beta+gamma)+cos gamma]` `=[2cos ((alpha+beta)/(2))cos((alpha-beta)/(2))]+[2cos((alpha+beta+2gamma)/(2))cos((alpha+beta)/(2))]` `=2cos((alpha+beta)/(2)).{cos((alpha-beta)/(2))+cos((alpha+beta+2gamma)/(2))}` `=2cos((alpha+beta)/(2)).{2cos((gamma+alpha)/(2))cos((beta+gamma)/(2))}` `=4cos ((alpha+beta)/(2))cos((beta+gamma)/(2))cos ((gamma+alpha)/(2))=` दायाँ पक्ष |
|