The sum of two unit vectors is a unit vector. The difference of the tw...
Explanation of Sum and Difference of Unit Vectors
Sum of Two Unit Vectors
Let us assume that two unit vectors are represented by a and b, then their sum is:
a + b = c
As per the question, c is also a unit vector:
|c| = 1
Therefore, we can write:
|a + b| = 1
Squaring both sides:
(a + b) . (a + b) = 1
Expanding the equation:
|a|² + 2a . b + |b|² = 1
Since a and b are unit vectors, we can write:
|a|² + 2a . b + |b|² = 1 + 1
Or,
2 + 2a . b = 2
Therefore, a . b = 0
This shows that the two unit vectors are perpendicular to each other.
Difference of Two Unit Vectors
Let us assume that two unit vectors are represented by a and b, then their difference is:
a - b = c
As per the question, we need to find the magnitude of c:
|c| = |a - b|
Using the distance formula, we can write:
|a - b| = √[(a₁-b₁)² + (a₂-b₂)² + (a₃-b₃)²]
As both a and b are unit vectors, their magnitude is 1:
Therefore,
|a - b| = √[(1-1)² + (1-1)² + (1-1)²]
Or,
|a - b| = √[0] = 0
Therefore, the magnitude of the difference of two unit vectors is 0.