`a(cosB+cosC) = 2(b+c)sin^2(A/2)`

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

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

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

(iii) a(b cosC - c cosB) = b^(2) -c^(2)

Prove that cosA -cosB -cosC =1-4sin(A/2)cos(B/2)cos(C/2) ,if A+B+C= pi

Which of the following holds goods for any tiangle ABC, a,b,c are the lengths of the sides R is circumradius (A) (cosA)/a+(cosB)/b+(cosC)/c= (a^2+b^2+c^2)/(2abc) (B) (sinA)/a+(sinB)/b+(sinC)/c=3/(2R0 (C) (cosA)/a=(cosB)/b=(cosC)/c (D) (sin2A)/a62=(sin2B)/b^2=(sin2C)/c^2

(v) 2(bc cosA + ca cosB + ab cosC) = a^(2) +b^(2)+c^(2)

In Delta ABC prove that 2(bc cosA + ca cosB + ab cosC) = a^2 + b^2 + c^2

Prove that (sin(B-C))/(cosB cosC)+(sin(C-A))/(cosC cosA)+(sin(A-B))/(cosA cosB) =0 .