If magnitude of sum of two unit vectors is √2 then find the magnitude ...
Solution
Let's consider two unit vectors A and B such that
- |A| = |B| = 1
- |A + B| = √2
Method 1: Using dot product
We know that dot product of two unit vectors is equal to cosine of the angle between them.
Let theta be the angle between A and B.
Then,
- A · B = cos(theta)
- |A + B|^2 = (A + B) · (A + B)
- |A + B|^2 = A · A + B · B + 2A · B
- |A + B|^2 = 2 + 2cos(theta)
- √2 = sqrt(2 + 2cos(theta))
- cos(theta) = 1/2
- theta = 60 degrees
Now, we can find the magnitude of the subtraction of these unit vectors using the cosine formula:
- |A - B|^2 = |A|^2 + |B|^2 - 2|A||B|cos(theta)
- |A - B|^2 = 2 - 2cos(theta)
- |A - B|^2 = 1
- |A - B| = 1
Method 2: Using vector algebra
We can write A and B in terms of their components as:
- A = i + j + k
- B = cos(theta)i + sin(theta)j
Using the fact that |A| = |B| = 1, we get:
- A · A = 1
- B · B = 1
- A · B = cos(theta) + sin(theta)
Now, we can find the magnitude of the subtraction of these unit vectors using the vector algebra:
- |A - B|^2 = (A - B) · (A - B)
- |A - B|^2 = A · A + B · B - 2A · B
- |A - B|^2 = 2 - 2cos(theta)
- |A - B|^2 = 1
- |A - B| = 1
Conclusion
Therefore, the magnitude of the subtraction of these unit vectors is 1.