`a(cosC-cosB)=2(b-c)cos^2A/2`

In DeltaABC , prove that: a(cosC-cosB)=2(b-c)cos^(2)A/2

In triangle ABC , prove that a(cosC-cosB)=2(b-c)cos^2.(A)/(2) .

Prove in any triangle ABC that (i) a(cos B+cos C)=2(b+c) "sin"^(2)(A)/(2) (ii) a(cos C- cosB)= 2(b-c )"cos"^(2)(A)/(2)

In DeltaABC , prove that: b(cosA-cosC)=2(c-a)cos^(2)B/2

In DeltaABC , prove that: a(cosB+cosC)=2(b+c)sin^(2)A/2 .

(b^2-c^2)/(cos B+cosC)+(c^2-a^2)/(cosC+cosA)+(a^2-b^2)/(cosA+cosB)=……

If A,B and C are angles of a triangle then the determinant |(-1,cosC,cosB),(cosC,-1,cosA),(cosB,cosA,-1)| is equal to

IN triangleABC, (cosC+cosA)/(c+a)+(cosB)/(b)=