Sorry if this isn't pre-calc, the education system over here is different =\ .
Just checking if I have this right as our instructions and teachings were a bit vague.
Question: Given that a = i + j and b = 2i + j, find the magnitude of each of the following vectors and the angle each makes with Ox.
(d) : 3a - 2b
Magnitude : sqrt(26)
Angle: 101.3 degrees (3sf)
From what I can see, the lengh on the x axis would be 1, while the height on the y-axis would be 1 as well. However, as it is -1i, it would be on the negative x axis. So does this make a difference to the normal way of working it out?
3(i+j) - 2(2i-j)
= (3i+3j) - (4i - 2j)
= |-i + 5j|
= sqrt(i^2 + 5^2)
angle = 180 - tan^-1(5)
angle = 101.3 degrees
The problem is, I'm not sure if I was supposed to do the 180- part or not?