Question

If $\overrightarrow{\lambda}$ is a unit vector perpendicular to plane of vector a and b and angle between them is θ, then a . b will be

• A. $|\mathbf{a}||\mathbf{b}|\sin\theta\overrightarrow{\lambda}$
• B. $|\mathbf{a}||\mathbf{b}|\cos{}\theta\overrightarrow{\lambda}$
• C. $|\mathbf{a}||\mathbf{b}|\cos{}\theta$
• D. $|\mathbf{a}||\mathbf{b}|\sin\theta$

Answer 1

Answer: (C)

$|\mathbf{a}||\mathbf{b}|\cos{}\theta$

Answer 2

It is obvious.