# dot-product and angle

- Author:
- Lukas Kehrer

- Topic:
- Angles

In this worksheet you will see how the dot-product is related to the angle between two vectors.

- Look at the triangle AFB. Try to express the line a with
and (use trigonometry)! - You see that a is eqal to the x-component of
and is equal to the x-component of . Now you can express the dot-product with , and . (notice that the y-component of is 0) - Proof what you found out in a few examples (Move around Point B) by comparing your result with the dot-product calculated above! (The results might not be exactly equal)
- Is your relation also right when you move point C?
- How could you calculate the lenght of line a without using the angle