(1+cos(A-B)cos C)/(1+cos(A-C)cos B)=(a^(2)+b^(2))/(a^(2)+c^(2))

(1+cos A*cos(B-C))/(1+cos C*cos(A-B))=(b^(2)+c^(2))/(a^(2)+b^(2))

In Delta ABC, show that (1-cos A+cos B+cos C)/(1-cos C+cos A+cos B)=tan((A)/(2))cot((C)/(2))

a(cos C-cos 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)

In any Delta ABC, 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

In /_ABC 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

If any triangle ABC, 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

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

If A,B,C are the angles of a triangle then prove that cos A+cos B-cos C=-1+4cos((A)/(2))cos((B)/(2))sin((C)/(2))

If A+B+C=pi then prove cos( (A)/2) cos( (B-C)/2) + cos( B/2) cos((C-A)/2) + cos( C/2) cos( (A-B)/2) = sinA +sinB+sinC