Question

If |Ã+ B²=A²+ B², then

(A) A and B must be parallel and in the same direction

(B) A and B must be parallel and in opposite directions

(C) either A or B must be zero

(D) the angle between A and B must be 90°

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Answer 1

answer - 90

Apply the formula used in Vector Addition

equate it to given eq

get cosX=0

X=90