CUET Preparation Today
If the difference of two unit vectors is again a unit vector, then the angle between them is ________. |
30° 45° 60° 90° |
60° |
The correct answer is Option (3) → 60° Let 'a' and 'b' be two unit vectors. $|a|=1,|b|=1$ and, $|a-b|=1$ also, $|a-b|=\sqrt{|a|^2+|b|^2-2|a||b|\cos θ}$ $1=2-2\cos θ$ $⇒\cos θ=\frac{1}{2}$ $⇒θ=\cos^{-1}(\frac{1}{2})=60°$ |
