Today we started with a homework quiz.
Then we proved why

We used Pythagorean theorem for the right triangle:

and we got that:
Then we used Pythagorean theorem for the left triangle:

also we used to get
Then we substituted everything from the left triangle in the equation we got for the right triangle. So the final equation is:
It works with SSS and SAS.

The next part of the unit were vectors.
In math the vector is a segment with direction, also called directed line segment:
The first point of the segment is called initial point (A), and the last point is called terminal point (B). a, b are components of the vector -
The length is sometimes referred to as magnitude,
Using Pythagorean theorem we could write it as:
The angle of the vector, θ is called direction angle.

examples:
1)Find the component form for a vector with initial point (-2,4) and terminal point (3,1).
The answer is <5,>

2)Find the component form for and θ=45º
, so
, so
The answer is

The rest of the class we went over hw.