Exam 39:Vectors and Dot Products

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Given vectors u=⟨u1,u2⟩\mathbf { u } = \left\langle u _ { 1 } , u _ { 2 } \right\rangle , v=⟨v1,v2⟩\mathbf { v } = \left\langle v _ { 1 } , v _ { 2 } \right\rangle and w=⟨w1,w2⟩\mathbf { w } = \left\langle w _ { 1 } , w _ { 2 } \right\rangle determine whether the result of the following expression is a vector or a scalar. 6w⋅3w6 w \cdot 3 w ​

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B

Find the angle between the vectors u and v.​ u=cos⁡(π3)i+sin⁡(π3)j\mathbf { u } = \cos \left( \frac { \pi } { 3 } \right) \mathbf { i } + \sin \left( \frac { \pi } { 3 } \right) \mathbf { j } , v=cos⁡(5π4)i+sin⁡(5π4)j\mathbf { v } = \cos \left( \frac { 5 \pi } { 4 } \right) \mathbf { i } + \sin \left( \frac { 5 \pi } { 4 } \right) \mathbf { j }

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D

Determine the work done by a crane lifting a 2,800-pound car 7 feet.

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A

Use the vector u=⟨3,2⟩\mathbf { u } = \langle 3,2 \rangle to find the indicated quantity.State whether the result is a vector or a scalar.​ u.u\mathbf { u } ^\mathbf{.}\mathbf { u } ^ { } ​

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​Find the projection of u onto v if , u=⟨−5,−4⟩\mathbf { u } = \langle - 5 , - 4 \rangle , v=⟨2,−5⟩\mathbf { v } = \langle 2 , - 5 \rangle .

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The vector u=⟨3900,4000⟩\mathbf { u } = \langle 3900,4000 \rangle gives the number of units of two models of laptops produced by a company.The vector u=⟨1450,1000⟩\mathbf { u } = \langle 1450,1000 \rangle gives the prices (in dollars)of the two models of laptops,respectively.Identify the vector operation used to increase revenue by 6%.

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Use vectors to find the measure of the angle at vertex B of triangle ABC,when A=(5,1)A = ( 5,1 ) , B=(−5,1)B = ( - 5,1 ) ,and C=(−3,−5)C = ( - 3 , - 5 ) .Round answer to two decimal places.

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Given u=⟨3,−2⟩\mathbf { u } = \langle 3 , - 2 \rangle and v=⟨1,−3⟩\mathbf { v } = \langle 1 , - 3 \rangle ,find u⋅vu\cdot v .

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Use the dot product to find the magnitude of u if u=−3i+6j\mathbf { u } = - 3 \mathbf { i } + 6 \mathbf { j }

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Determine whether u are v and orthogonal,parallel,or neither. u=⟨−43,32⟩,v=⟨16,−18⟩\mathbf { u } = \left\langle \frac { - 4 } { 3 } , \frac { 3 } { 2 } \right\rangle , \mathbf { v } = \langle 16 , - 18 \rangle

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Determine u.vu^.v if ∥u∥=5,∥v∥=6\| \mathbf { u } \| = 5 , \| \mathbf { v } \| = 6 ,and θ=π3\theta = \frac { \pi } { 3 } where θ is the angle between u and v.Round answer to two decimal places.

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Determine whether u are v and orthogonal,parallel,or neither. u=⟨13,52⟩\mathbf { u } = \left\langle \frac { 1 } { 3 } , \frac { 5 } { 2 } \right\rangle , v=⟨−4,−30⟩\mathbf { v } = \langle - 4 , - 30 \rangle

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A force of 45 pounds is exerted along a rope attached to a crate at an angle of 30° above the horizontal.The crate is moved 31 feet horizontally.How much work has been accomplished? Round your answer to one decimal place.

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Find the angle θ between the vectors.​ =\langle6,2\rangle =\langle7,0\rangle ​ (Round the answer to 2 decimal places. ) ​

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Find the projection of u onto v.​ =\langle-5,-5\rangle =\langle-5,-1\rangle ​

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Find the projection of u onto v.Then write u as the sum of two orthogonal vectors,one of which is proj⁡vu\operatorname { proj } _ { \mathrm { v } } \mathbf { u } .​ ​​ u=⟨30,5⟩\mathbf { u } = \langle 30,5 \rangle v=⟨1,−6⟩\mathbf { v } = \langle 1 , - 6 \rangle ​

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Find the projection of u onto v.​ =\langle0,4\rangle =\langle3,20\rangle ​

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Find the angle between the vectors u and v if u=3i−2j\mathbf { u } = 3 \mathbf { i } - 2 \mathbf { j } and u=3i+2j\mathbf { u } = 3 \mathbf { i } + 2 \mathbf { j } Round your answer to two decimal places.

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Use the vectors u=⟨2,4⟩\mathbf { u } = \langle 2,4 \rangle , v=⟨−5,3⟩\mathbf { v } = \langle - 5,3 \rangle and w=⟨3,−1⟩\mathbf { w } = \langle 3 , - 1 \rangle to find the indicated quantity.State whether the result is a vector or a scalar.​ (v.u)−(w.v)\left( \mathbf { v } ^ { . } \mathbf { u } \right) - \left( \mathbf { w } ^ { . } \mathbf { v } \right) ​

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Given vectors u=⟨−1,3⟩\mathbf { u } = \langle - 1,3 \rangle and v=⟨1,4⟩\mathbf { v } = \langle 1,4 \rangle determine the quantity indicated below. −2u⋅−4v- 2 \mathbf { u }{ \cdot}- 4 \mathbf { v }

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