Respuesta :
Answer:
Angle between the two vectors is 135°
u•v = -12
Step-by-step explanation:
Given two vectors u = (4,0) and v = (-3,-3).
To find the angle between the two vectors we will use the formula for calculating the angle between two vectors as shown;
u•v = |u||v|cos theta
cos theta = u•v/|u||v|
theta = arccos (u•v/|u||v|)
u•v = (4,0)•(-3,-3)
u•v = 4(-3)+0(-3)
u•v = -12
For |u| and |v|
|u| = √4²+0²
|u| = √16 = 4
|v| = √(-3)²+(-3)²
|v| = √9+9
|v| = √18
|v| = 3√2
|u||v| = 4×3√2 = 12√2
theta = arccos(-12/12√2)
theta = arccos(- 1/√2)
theta = -45°
Since cos is negative in the second quadrant, theta = 180-45°
theta = 135°
To get u•v using the formula u•v = |u||v|cos theta
Given |u||v| = 12√2 and theta = 135°
u•v = 12√2cos 135°
u•v = 12√2× -1/√2
u•v = -12√2/√2
u•v = -12
For the diagram of the vectors, find it in the attachment below.

Answer:
Check the graph below for the sketch.
[tex]\theta=135^{\circ}[/tex]
Step-by-step explanation:
1) Let's organize the data from these Latex codes.
[tex]\vec{\mathbf{u}}=\left \langle 4,0 \right \rangle\:and\: \vec{\mathbf{v}}=\left \langle -3,-3 \right \rangle[/tex]
2) Sketching them (Check below). Notice that we are going to use the coordinates of each vector.
3) To find the angle between the vectors, we need to remember the Theorem:
If there is an angle between two vectors a and b, then we can calculate its angle using this relation:
[tex]a*b=\left \| a \right \|\left \| b \right \|*cos\theta[/tex]
3.1) Then we need the Dot product between u and v. The Dot product is going to give us a scalar value for a product between vectors.
We will also need the norm of each vector. The norm will tell us the length of each one.
[tex]\vec{u}*\vec{v}=\vec{u}*\vec{v}=4(-3)+0(-3)=-12\\\left \| u \right \|=\sqrt{4^2+0^2 }= \left \| u \right \|=4, \\\left \| v \right \|=\sqrt{(-3)^2+(-3)^2}, \left \| v \right \|=18=3\sqrt{2} \left\\[/tex]
3.2)
Now, we can plug these pieces of information from 3.1 and 3.2 and find the angle:
[tex]cos\theta=\frac{uv}{\left \| u \right \|\left \| v \right \|}=\frac{4*-3+(0)(-3)}{12\sqrt{2} }=\frac{-12}{ 12\sqrt{2} }\\\theta=cos^{-1}(\frac{-12}{ 12\sqrt{2} })\rightarrow \theta\approx 135^{\circ}[/tex]

