Blog 9: Adding or Subtracting Vectors

There are two main ways to go about adding or subtracting vectors:

1. Use a scale diagram

a) Measure and draw vectors in scale (1cm=1km)
b) Connect the head to tail
c) Resultant is always origin to destination (AYJackson to PMall :P)
d) When you "subtract" vectors, you are actually adding in the opposite direction (12km[N] can be rewritten as -12km[S])

e) Use a protractor to measure the angle in accordance to North and South.

2. Add or subtract by components

a) Set you positive axes

b) Break all vectors into two components (x and y)

c) Solve for ∑x and ∑y (summation of x and y)

d) Use Pythagorean Theorem to add the two sums of components (∑x and ∑y)

e) Use trigonometry to solve for angle

        SOH → sinθ = opp/hyp

        CAH → cosθ = adj/hyp

        TOA → tanθ = sinθ/cosθ = opp/adj