Question

The angle between two vectors P→ and Q→ of magnitudes 3 and 5 units is 600. What is the dot product of the two vectors?

Answer 1

Answer:

7.5

Explanation:

a. b=|a| |b|cos60

=(3)(5)1/2

=15/2

=7.5

Answer 2

Answer:

$\frac{15}{2}$

Explanation:

We are given that

Angle between two vectors P and Q=$60^{\circ}$

$\mid P\mid=3 units$

$mid Q\mid=5 units$

We have to find the dot product of two vectors

We know that

$cos\theta=\frac{a\cdot b}{\mid a\mid \mid b\mid}$

Using the formula

$cos 60^{\circ}=\frac{P\cdot Q}{3\times 5}$

$\frac{1}{2}=\frac{P\cdot Q}{15}$

$P\codt Q=\frac{15}{2}$

Hence, the dot product of the two vectors=$\frac{15}{2}$