किसी `triangleABC` में सिद्ध करें कि
`(cosA)/(a) + (cosB)/(b) + (cosC)/(c) = (a^(2) + b^(2) +c^(2))/(2abc)`

Explanation

बायाँ पक्ष ` = (cosA)/(a) + (cosB)/(b) + (cosC)/(c)`
` = (b^(2) +c^(2)-a^(2))/(2bcxxa) +(a^(2)+c^(2)-b^(2))/(2ac+b) + (a^(2)+b^(2)-c^(2))/(2abxxc)`
` = (1)/(2abc) (b^(2) +c^(2) -a^(2) +a^(2) +c^(2) -b^(2) +a^(2) +b^(2) -c^(2))`
` = (a^(2)+b^(2)+c^(2))/(2abc)` = दायाँ पक्ष