Cross Product Formula

The cross product or vector product is a binary operation on two vectors in three-dimensional space (R3) and is denoted by the symbol x. Two linearly independent vectors a and b, the cross product, a x b, is a vector that is perpendicular to both a and b and therefore normal to the plane containing them. 

Cross Product FormulaCross Product is given by,

\[\LARGE A\times B=\begin{vmatrix} i & j & k\\ a_{1} & a_{2}& a_{3} \\ b_{1} & b_{2}& b_{3} \end{vmatrix}\]

a1, a2, a3 are the components of the vector $\overrightarrow{a}$  and b1, b2 and b3 are the components of $\overrightarrow{b}$ .

Cross Product Formula is given by,

\[\LARGE a\times b=\left | a \right |\left | b \right |\sin \theta\]

Cross product formula is used to determine the cross product or angle between any two vectors based on the given problem.

Solved Examples

Question 1:Calculate the cross products of vectors a = <3, 4, 7> and b = <4, 9, 2>.


The given vectors are, a = (3, 4, 7) and b = (4, 9, 2)
The cross product is given by
a $\times$ b =$\begin{vmatrix} i & j & k\\ a_{1} & a_{2}& a_{3} \\ b_{1} & b_{2}& b_{3} \end{vmatrix}$

a $\times$ b = $\begin{vmatrix} i & j & k \\3 & 4 & 7 \\4 & 9 & 2 \end{vmatrix}$

a $\times$ b = $i(4\times 2-9\times 7)-j(3 \times 2 – 4\times 7)+k(3\times 9-4\times 9)$

a $\times$ b = $i(8-63)-j(6-28)+k(27-36)$

a $\times$ b = $-55i+22j-9k$

Practise This Question

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