Vector Addition and Subtraction Answers

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Let u = ⟨9, –2⟩, v = ⟨–4, 3⟩, and w = ⟨5, 1⟩. Kelcy incorrectly determined 3u – 5(v + w) to be ⟨32, –26⟩. Review her steps as shown.3u – 5(v + w)3⟨9, –2⟩ – 5[⟨–4, 3⟩ + ⟨5, 1⟩]⟨27, –6⟩ – 5[⟨–1, 4⟩]⟨27, –6⟩ + ⟨5, –20⟩⟨32, –26⟩

A
She added ⟨–4, 3⟩ and ⟨5, 1⟩ incorrectly.
B
She did not correctly distribute 3 to both components of u.
C
She should have distributed –5 to both v and w before adding.
D
She should have subtracted ⟨27, –6⟩ and ⟨5, –20⟩, rather than adding.
4

Let |u| = 10 at an angle of 45° and |v| = 13 at an angle of 150°, and w = u + v. What is the magnitude and direction angle of w?

A
|w| = 9.4; θ = 72.9°
B
|w| = 9.4; θ = 107.1°
C
|w| = 14.2; θ = 72.9°
D
|w| = 14.2; θ = 107.1°
6

Let r = ⟨7, 1⟩ and s = ⟨–12, –3⟩. What is r – s?

A
⟨–19, –4⟩
B
⟨–5, –2⟩
C
⟨10, 13⟩
D
⟨19, 4⟩
7

Let a = ⟨5, –9⟩ and b = ⟨–3, 1⟩, and c = b – a. What is the magnitude and direction angle of c?

A
|c| = 12.8; θ = 128.7°
B
|c| = 18.0; θ = 128.7°
C
|c| = 12.8; θ = 308.7°
D
|c| = 18.0; θ = 308.7°

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