If the magnitude of two vectors is 4 and 5 and the value of their scalar product is 10, then the angle between vectors is:

The correct option is C: 60^o

Let magnitude of two vectors as : $\left|\overrightarrow{a}\right|=4,\left|\overrightarrow{b}\right|=5$

The value of their scalar product is 10

$\Rightarrow \overrightarrow{a}.\overrightarrow{b}=10$

Using formula we get:

$\Rightarrow \overrightarrow{a}.\overrightarrow{b}=\left|\overrightarrow{a}\right|\left|\overrightarrow{b}\right|cos\theta$

$\Rightarrow 10=4\times 5\times cos\theta$

$\Rightarrow cos\theta =\frac{1}{2}$

$\Rightarrow \theta ={60}^o$