`(cos^2B-cos^2C)/(b+c)+(cos^2C-cos^2A)/(c+a)+(cos^2A-cos^2B)/(a+b)=0`

In any triangle ABC, prove that following: (cos^(2)B-cos^(2)C)/(b+c)+(cos^(2)C-cos^(2)A)/(c+a)+(cos^(2)A-cos^(2)B)/(a+b)=0

a^2(cos^2B-cos^2C)+b^2(cos^2C-cos^2A)+c^2(cos^2A-cos^2B)=0 .

In /_\ABC prove that a^2(cos^2B-cos^2C)+b^2(cos^2C-cos^2A)+c^2(cos^2A-cos^2B) = 0

In Delta ABC prove that a^2(cos^2B - cos^2C) + b^2(cos^2C - cos^2A) + c^2(cos^2A - cos^2B) = 0

a^(2)(cos^(2)B-cos^(2)C)+b^(2)(cos^(2)C-cos^(2)A)+c^(2)(cos^(2)A-cos^(2)B)=0

In any Delta ABC, prove that :a^(2)(cos^(2)B-cos^(2)C)+b^(2)(cos^(2)C-cos^(2)A)+c^(2)(cos^(2)A-cos^(2)B)=0

(iv) a^(2)(cos^(2) B - cos^(2)C) + b^(2) (cos^(2) C- cos^(2)A) + c^(2) (cos^(2)A- cos^(2)B)=0

In any DeltaABC , prove that : (b^2 - c^2)/(cos B + cos C) + (c^2 - a^2)/(cos C + cos A) + (a^2 - b^2)/(cos A + cos B) = 0

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

If A+B +C =2S, prove that : cos^2 S + cos^2 (S- A) + cos^2 (S-B)+ cos^2 (S -C) = 2 +2 cos A cos B cos C .