Answer:

Since the angle between the two vectors is not 180 or 0 degrees we can conclude that are not parallel
And the anfle is approximately 
Step-by-step explanation:
For this case first we need to calculate the dot product of the vectors, and after this if the dot product is not equal to 0 we can calculate the angle between the two vectors in order to see if there are parallel or not.
a=[1,2,-2], b=[4,0,-3,]
The dot product on this case is:

Since the dot product is not equal to zero then the two vectors are not orthogonal.
Now we can calculate the magnitude of each vector like this:


And finally we can calculate the angle between the vectors like this:

And the angle is given by:

If we replace we got:

Since the angle between the two vectors is not 180 or 0 degrees we can conclude that are not parallel
And the anfle is approximately 
You can calculate it using the law of cosines: c^2=a^2+b^2-2*a*b*cos(C)
your triangle is
CD=15=a
CE=?=b
DE=CE+3=b+3=c
and C=90°
-> insert those values, with c substituted with b+3 to remove c
c^2=a^2+b^2-2*a*b*cos(C)
(b+3)^2=15^2+b^2-2*15*b*cos(90)
cos(90)=0->
(b+3)^2=15^2+b^2
b^2+2*3*b+3^2=225+b^2
6b+9=225
6b=216
b=36=CE
DE=CE+3=36+3=39
3.3333333333333333333
repeating
Answer: 12 guests
Step-by-step explanation:
Take 36 (silverware) and divide by three (spoon fork and knife) and you will get 12!