" 7."c(cos B-cos A)=2(a-b)cos^(2)(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 : (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)

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)

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

In a Delta ABC if (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))/(Kabc) then K^(k) is equal to

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

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))