The angle between the vectors (i+j) and (j+k) is

Options

(a) 90⁰
(b) 60⁰
(c) 30⁰
(d) 45⁰

Correct Answer:

60⁰

Explanation:

A = i + j, B = j + k

A . B = |A| |B| cos θ

where θ is the angle between two vectors A and B.

.·. A.B = (i + j).(j + k) = 1

|A| = √(1² + 1²) = √2,

|B| = √(1² + 1²) = √2

.·. cos θ = A.B / |A| |B| = 1/(√2×√2) = 1/2

θ = cos⁻¹ (1/2) = 60⁰