Find the angle θ between vectors r and s, where |r| = 16, |s| = 9, and r · s = 125.
Answer
A
θ = 85.87°
B
θ = 82.65°
C
θ = 29.77°
D
θ = 16.26°
Explanation
Use the dot product formula r · s = |r||s| cos θ. Then cos θ = 125 ÷ (16 × 9) = 125/144 ≈ 0.8681, so θ = cos⁻¹(0.8681) ≈ 29.77°. The correct choice is θ = 29.77°.
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