(ii)quad a(cos C-cos B)=2(b-c)cos^(2)(A)/(2)

In any DelataABC prove that "a(cos C - cos B)=2(b-c)cos"^(2)A/2

In any triangle ABC, prove that : a (cos C - cos B) = 2 (b-c) cos^2 frac (A)(2) .

In DeltaABC , prove that: a(cos^(2)C/2-cos^(2)B/2)=(b-c).cos^(2)A/2

In any Delta ABC, prove the following: (a+b+c)(cos A+cos B+cos C)=2((a cos^(2))(1)/(2)(A+b cos^(2))(1)/(2)(B+cos^(2))(1)/(2)C)

b(cos A-a cos C)=c^(2)-a^(2)

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

a (cos B + cos C) = 2 (b + c) sin ^ (2) ((A) / (2))

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 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)