In `DeltaABC`, prove that `a^2 + b^2 +c^2 = 2(bc cos A+ cacos B+ ab cos C)`

In any DeltaABC , prove that : a^2 +b^2 +c^2 = 2 (bc cos A + ca cos B + ab cos C) .

In Delta ABC prove that a^(2)+b^(2)+c^(2)=2(bc cos A+ca cos B+ab cos C)

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

Prove that a^(2)+b^(2)+c^(2)=2(ab cos C +bc cosA +ca cos B)

In any DeltaABC , 2 (bc cos A + ca cos B + ab cos C) =

In any DeltaABC prove by vectors that a^2=b^2+c^2-2 bc cos A.

Prove in any triangle ABC that (i) a^(2)+b^(2)+c^(2)=2(bc cos A +ca cos B+ ab cos C) (ii) (b+c) cos A+(c+a)cos B+(a+b) cos C = a+b+c .

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

In any DeltaABC , prove that : a cos A + b cos B + c cos C = 2a sin B sin C

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