Question

Vector 𝐴⃗ has a magnitude of 5.00 units, and vector B ⃗ has a magnitude of 9.00 units. 

The two vectors make an angle of 50.0° with each other. Find 𝐴⃗ •B ⃗. 

Answer 1

The dot product is

$$\vec A·\vec B=5·9\cos50°=28.9.$$