Answer:
Let, θ be the angle between vector a and vector b.
So, the angle between vector a and vector (-b) must be (180° - θ).
Magnitude of the difference of vectors a and b
= |a - b|
= Magnitude of the resultant of the vector sum of the vectors a and (-b)
= |{√|a|^2 + |b|^2 + 2 * |a| * |b| * cos (180° - θ)}|
= |{√|a|^2 + |b|^2 - 2 * |a| * |b| * (cos θ)}|.
Explanation: