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Multiple Choice
If vectors ∣a⃗∣=3 and ∣b⃗∣=7, and a⃗⋅b⃗=14.85, determine the angle between vectors a⃗ and b⃗.
A
21°
B
1.0°
C
45°
D
14.85°
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Verified step by step guidance
1
Start by recalling the formula for the dot product of two vectors: \( a \cdot b = |a| |b| \cos(\theta) \), where \( \theta \) is the angle between the vectors.
Substitute the given values into the formula: \( 14.85 = 3 \times 7 \times \cos(\theta) \).
Simplify the equation: \( 14.85 = 21 \cos(\theta) \).
Solve for \( \cos(\theta) \) by dividing both sides of the equation by 21: \( \cos(\theta) = \frac{14.85}{21} \).
Use the inverse cosine function to find \( \theta \): \( \theta = \cos^{-1}\left(\frac{14.85}{21}\right) \).