4*(c-b cos A)/(b-ccos A)=(cos B)/(cos C)

(c-b cos A)/(b-c cos A)=(cos B)/(cos C)

In any Delta ABC, prove that : (cos A)/(b cos C+c cos B)+(cos B)/(c cos A+a cos C)+(cos C)/(c cos B+b cos A)=(a^(2)+b^(2)+c^(2))/(2abc)

If A+B+C=180^(@) then cos2A+cos2B+cos2C=1-4cos A cos B cos C 2.If A+B+C=0 then cos A+cos B+cos C=-1+4(cos A)/(2)(cos B)/(2)(cos C)/(2)

In any triangle ABC, prove that following: a(cos B cos C+cos A)=b(cos C cos A+cos B)=c(cos A cos B+cos C)

In any triangle A B C , prove that following: \ a\ (cosB cos C+cos A)=b(cos C\ cos A+cos B)=c(cos A\ cos B+cos C)dot

(a + b + c) (cos A + cos B + cos C)

( cos A) /( a) + ( cos B) /( b ) + ( cos C ) /( c )

Prove that (cos C + cos A)/(c + a) + (cos B)/(b) = (1)/(b)