EasyPhysics1Units and Measurements, Mathematical Tools
+4 / -1
If A = î + ĵ and B = î − k̂, the angle between A and B is
A
zero
B
180°
C
60°
D
90°
Explanation
Use the dot product formula: A · B = |A||B| cosθ. A = (1,1,0), B = (1,0,−1). A · B = (1)(1) + (1)(0) + (0)(−1) = 1 |A| = √(1² + 1² + 0²) = √2, |B| = √(1² + 0² + (−1)²) = √2 cosθ = (A·B)/(|A||B|) = 1/(√2 × √2) = 1/2 θ = 60°.
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