The angle between the unit vectors $\mathbf{a}$ and $\mathbf{b}$ is $\theta$. By expanding the

Question

The angle between the unit vectors $\mathbf{a}$ and $\mathbf{b}$ is $\theta$. By expanding the scalar product, show that $(4\mathbf{a}-\mathbf{b})\cdot(\mathbf{a}+4\mathbf{b})=15\cos\theta$.

Accepted Answer

$15 cos \theta $

Vectors - Scalar (Dot) Product

Vectors - Scalar (Dot) Product

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