5
QuizMultiple Choice

Dot Product and Work

Question 5 • Precalculus

Given vectors u = ⟨2, –3⟩ and v = ⟨1, –1⟩, what is the measure of the angle between the vectors?

Answer
A
11.3°
B
78.9°
C
92.2°
D
101.3°

Explanation

Use the dot product formula: cos θ = (u · v) / (|u||v|). The dot product is 2(1) + (−3)(−1) = 5, and the vector lengths are √13 and √2, so cos θ = 5/√26. Taking the inverse cosine gives θ ≈ 11.3°, so the angle is choice A, 11.3°.

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