Unknowns in basic vectors [closed]

0

$begingroup$

Haven't touched vectors for years and need some help with the following

Given $ u = 3i + 2j$ and $ v = 2i + lambda j$, find values for $lambda$ such that

a) the angle between $ u$ and $ v$ is $frac{pi}{4}$

b) the length of projection of $u$ on $v$ is 2 units.

Any help is appreciated. Thanks!

vectors

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edited Jan 9 at 9:13

Polarmagic

asked Jan 9 at 8:45

PolarmagicPolarmagic

32

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closed as off-topic by mrtaurho, drhab, José Carlos Santos, verret, Eevee Trainer Jan 10 at 2:47

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – mrtaurho, drhab, José Carlos Santos, verret, Eevee Trainer

If this question can be reworded to fit the rules in the help center, please edit the question.

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  give it a try first? try to read up on how to compute angle and length?
  $endgroup$
  – Siong Thye Goh
  Jan 9 at 8:49
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Welcome to Math.SE. Take a look at How to ask a good question at Math.SE. To avoid downvotes and closing you should add your own efforts to the question, and tell us where you got stuck.
  $endgroup$
  – drhab
  Jan 9 at 8:59
  

  
  
  
  

add a comment | 

0

$begingroup$

Haven't touched vectors for years and need some help with the following

Given $ u = 3i + 2j$ and $ v = 2i + lambda j$, find values for $lambda$ such that

a) the angle between $ u$ and $ v$ is $frac{pi}{4}$

b) the length of projection of $u$ on $v$ is 2 units.

Any help is appreciated. Thanks!

vectors

share|cite|improve this question

edited Jan 9 at 9:13

Polarmagic

asked Jan 9 at 8:45

PolarmagicPolarmagic

32

$endgroup$

closed as off-topic by mrtaurho, drhab, José Carlos Santos, verret, Eevee Trainer Jan 10 at 2:47

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – mrtaurho, drhab, José Carlos Santos, verret, Eevee Trainer

If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  give it a try first? try to read up on how to compute angle and length?
  $endgroup$
  – Siong Thye Goh
  Jan 9 at 8:49
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Welcome to Math.SE. Take a look at How to ask a good question at Math.SE. To avoid downvotes and closing you should add your own efforts to the question, and tell us where you got stuck.
  $endgroup$
  – drhab
  Jan 9 at 8:59
  

  
  
  
  

add a comment | 

0

0

0

$begingroup$

Haven't touched vectors for years and need some help with the following

Given $ u = 3i + 2j$ and $ v = 2i + lambda j$, find values for $lambda$ such that

a) the angle between $ u$ and $ v$ is $frac{pi}{4}$

b) the length of projection of $u$ on $v$ is 2 units.

Any help is appreciated. Thanks!

vectors

share|cite|improve this question

edited Jan 9 at 9:13

Polarmagic

asked Jan 9 at 8:45

PolarmagicPolarmagic

32

$endgroup$

Haven't touched vectors for years and need some help with the following

Given $ u = 3i + 2j$ and $ v = 2i + lambda j$, find values for $lambda$ such that

a) the angle between $ u$ and $ v$ is $frac{pi}{4}$

b) the length of projection of $u$ on $v$ is 2 units.

Any help is appreciated. Thanks!

vectors

vectors

share|cite|improve this question

edited Jan 9 at 9:13

Polarmagic

asked Jan 9 at 8:45

PolarmagicPolarmagic

32

share|cite|improve this question

edited Jan 9 at 9:13

Polarmagic

asked Jan 9 at 8:45

PolarmagicPolarmagic

32

share|cite|improve this question

share|cite|improve this question

edited Jan 9 at 9:13

Polarmagic

edited Jan 9 at 9:13

Polarmagic

edited Jan 9 at 9:13

Polarmagic

asked Jan 9 at 8:45

PolarmagicPolarmagic

32

asked Jan 9 at 8:45

PolarmagicPolarmagic

32

asked Jan 9 at 8:45

PolarmagicPolarmagic

32

32

closed as off-topic by mrtaurho, drhab, José Carlos Santos, verret, Eevee Trainer Jan 10 at 2:47

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – mrtaurho, drhab, José Carlos Santos, verret, Eevee Trainer

If this question can be reworded to fit the rules in the help center, please edit the question.

closed as off-topic by mrtaurho, drhab, José Carlos Santos, verret, Eevee Trainer Jan 10 at 2:47

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – mrtaurho, drhab, José Carlos Santos, verret, Eevee Trainer

If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  give it a try first? try to read up on how to compute angle and length?
  $endgroup$
  – Siong Thye Goh
  Jan 9 at 8:49
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Welcome to Math.SE. Take a look at How to ask a good question at Math.SE. To avoid downvotes and closing you should add your own efforts to the question, and tell us where you got stuck.
  $endgroup$
  – drhab
  Jan 9 at 8:59
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  give it a try first? try to read up on how to compute angle and length?
  $endgroup$
  – Siong Thye Goh
  Jan 9 at 8:49
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Welcome to Math.SE. Take a look at How to ask a good question at Math.SE. To avoid downvotes and closing you should add your own efforts to the question, and tell us where you got stuck.
  $endgroup$
  – drhab
  Jan 9 at 8:59
  

  
  
  
  

1

1

$begingroup$
give it a try first? try to read up on how to compute angle and length?
$endgroup$
– Siong Thye Goh
Jan 9 at 8:49

$begingroup$
give it a try first? try to read up on how to compute angle and length?
$endgroup$
– Siong Thye Goh
Jan 9 at 8:49

$begingroup$
Welcome to Math.SE. Take a look at How to ask a good question at Math.SE. To avoid downvotes and closing you should add your own efforts to the question, and tell us where you got stuck.
$endgroup$
– drhab
Jan 9 at 8:59

$begingroup$
Welcome to Math.SE. Take a look at How to ask a good question at Math.SE. To avoid downvotes and closing you should add your own efforts to the question, and tell us where you got stuck.
$endgroup$
– drhab
Jan 9 at 8:59

add a comment | 

1 Answer
1

active

oldest

votes

1

$begingroup$

Hints:

• a) $(u,v)=||u||||v||costheta$
  


• b) If $w$ is the projection of $u$ on $v$ then $w=rho v$ for some scalar $rho$ and $(u-w)bot v$ (express this by means of inproduct).

share|cite|improve this answer

edited Jan 11 at 8:31

answered Jan 9 at 8:58

drhabdrhab

100k544130

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add a comment | 

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

active

oldest

votes

active

oldest

votes

1

$begingroup$

Hints:

• a) $(u,v)=||u||||v||costheta$
  


• b) If $w$ is the projection of $u$ on $v$ then $w=rho v$ for some scalar $rho$ and $(u-w)bot v$ (express this by means of inproduct).

share|cite|improve this answer

edited Jan 11 at 8:31

answered Jan 9 at 8:58

drhabdrhab

100k544130

$endgroup$

add a comment | 

1

$begingroup$

Hints:

• a) $(u,v)=||u||||v||costheta$
  


• b) If $w$ is the projection of $u$ on $v$ then $w=rho v$ for some scalar $rho$ and $(u-w)bot v$ (express this by means of inproduct).

share|cite|improve this answer

edited Jan 11 at 8:31

answered Jan 9 at 8:58

drhabdrhab

100k544130

$endgroup$

add a comment | 

1

1

1

$begingroup$

Hints:

• a) $(u,v)=||u||||v||costheta$
  


• b) If $w$ is the projection of $u$ on $v$ then $w=rho v$ for some scalar $rho$ and $(u-w)bot v$ (express this by means of inproduct).

share|cite|improve this answer

edited Jan 11 at 8:31

answered Jan 9 at 8:58

drhabdrhab

100k544130

$endgroup$

Hints:

• a) $(u,v)=||u||||v||costheta$
  


• b) If $w$ is the projection of $u$ on $v$ then $w=rho v$ for some scalar $rho$ and $(u-w)bot v$ (express this by means of inproduct).

share|cite|improve this answer

edited Jan 11 at 8:31

answered Jan 9 at 8:58

drhabdrhab

100k544130

share|cite|improve this answer

share|cite|improve this answer

edited Jan 11 at 8:31

edited Jan 11 at 8:31

edited Jan 11 at 8:31

answered Jan 9 at 8:58

drhabdrhab

100k544130

answered Jan 9 at 8:58

drhabdrhab

100k544130

answered Jan 9 at 8:58

drhabdrhab

100k544130

100k544130

add a comment | 

add a comment | 

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