If `A, B, C` and `D` are four points and `bar (AB) = bar (DC)` then `bar (AC) +bar (BD) =` (A) `2vec(AD)` (B) `2vec(CB)` (C) `2vec(AC)` (D) none

If A, B, C and D aare four points and vec AB = vec DC then vec AC + vec BD =

If A,B,C,D are four point and |bar(AB) xx bar(CD) +bar(BC)xx bar(AD) +bar(CA) xx bar(BD)| = k ("Area of "DeltaABC) , then k =

If ABCD is a parallelogram such that bar(AB)=bar(a), bar(BC)=bar(b)" then "bar(AC), bar(BD) are

If A,B, C and D are four points, then show that |bar(AB) xx bar(CD) + bar(BC) xx bar(AD) + bar(CA) xx bar(BD)| is four times the area of Delta ABC

In the parallelogram if bar(AB)=bar(a) and bar(AD)=bar(d) then find bar(BD) .

If A, B, C, D be any four points and E and F be the middle points of AC and BD respectively, then A vec(B) + C vec(B) +C vec (D) + vec(AD) is equal to

If A, B, C, D and E are five coplanar points, then the value of bar(DA)+bar(DB)+bar(DC) + bar(AE) +bar( BE) +bar (CE) is equal to

If A,B,C,D are four points in space satisfying bar(AB).bar(CD)=k[|bar(AD)|^(2)+|bar(BC)|^(2)-|bar(AC)|^(2)-|bar(BD)|^(2)] then k =

vec(AC) and vec(BD) are the diagonals of a parallelogram ABCD. Prove that (i) vec(AC) + vec(BD) - 2 vec(BC) (ii) vec(AC) - vec(BD) - 2vec(AB)

A,B,C,D are four points in space and |bar(AB) times bar(CD) +bar(BC) times bar(AD)+bar(CA) times bar(BD)|=lamda (area DeltaABC ) then value of lamda is _____