Question Detail

PHY 101 PHY 101 Past Questions Objective Question
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Question

Find the angle between the two vectors A = 2i + 3j + k and B = -4i + 2j - k.
Options
A 100.1°
Correct Answer
B 90.1°
C 78.5°
D 65.2°
Correct Answer

Option A is the correct answer.

Detailed Explanation

A·B = (2)(-4) + (3)(2) + (1)(-1) = -8 + 6 - 1 = -3. |A| = √(4+9+1)=√14 ≈ 3.742. |B| = √(16+4+1)=√21 ≈ 4.583. cos θ = -3 / (3.742 * 4.583) = -3 / 17.15 = -0.175. θ = arccos(-0.175) ≈ 100.1°.

Hint

Use the dot product formula: A·B = |A||B| cos θ.

Question Info

Course: PHY 101
Topic: PHY 101 Past Questions
Type: Objective
Difficulty: Not specified
Question 1186 of 1250
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