Is this a sign for dot product? [closed]

Clash Royale CLAN TAG#URR8PPP

up vote
1
down vote

favorite

Whenever we write $cos(hattextbfn,z)<0$ do we mean that the angle between the unit normal and the $z$ axis is greater than 90$^circ$?

Or is it some sort of reference to the dot product? Context:

linear-algebra vector-spaces notation vectors

share|cite|improve this question

edited Jul 17 at 21:43

asked Jul 17 at 20:46

Bak1139

1,39921128

closed as unclear what you're asking by m_t_, amWhy, Xander Henderson, Trần Thúc Minh Trí, max_zorn Jul 18 at 4:27

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Probably the former, but maybe not "whenever". Edit the question to provide the context.
  – Ethan Bolker
  Jul 17 at 20:51
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  I have never seen that notation.
  – copper.hat
  Jul 17 at 20:51
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  How do we usually set the angle between the z axis and a vector? From the z unit vector counter clockwise ?
  – Bak1139
  Jul 17 at 20:53
  

  
  
  
  

add a comment | 

up vote
1
down vote

favorite

Whenever we write $cos(hattextbfn,z)<0$ do we mean that the angle between the unit normal and the $z$ axis is greater than 90$^circ$?

Or is it some sort of reference to the dot product? Context:

linear-algebra vector-spaces notation vectors

share|cite|improve this question

edited Jul 17 at 21:43

asked Jul 17 at 20:46

Bak1139

1,39921128

closed as unclear what you're asking by m_t_, amWhy, Xander Henderson, Trần Thúc Minh Trí, max_zorn Jul 18 at 4:27

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Probably the former, but maybe not "whenever". Edit the question to provide the context.
  – Ethan Bolker
  Jul 17 at 20:51
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  I have never seen that notation.
  – copper.hat
  Jul 17 at 20:51
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  How do we usually set the angle between the z axis and a vector? From the z unit vector counter clockwise ?
  – Bak1139
  Jul 17 at 20:53
  

  
  
  
  

add a comment | 

up vote
1
down vote

favorite

up vote
1
down vote

favorite

Whenever we write $cos(hattextbfn,z)<0$ do we mean that the angle between the unit normal and the $z$ axis is greater than 90$^circ$?

Or is it some sort of reference to the dot product? Context:

linear-algebra vector-spaces notation vectors

share|cite|improve this question

edited Jul 17 at 21:43

asked Jul 17 at 20:46

Bak1139

1,39921128

Whenever we write $cos(hattextbfn,z)<0$ do we mean that the angle between the unit normal and the $z$ axis is greater than 90$^circ$?

Or is it some sort of reference to the dot product? Context:

linear-algebra vector-spaces notation vectors

share|cite|improve this question

edited Jul 17 at 21:43

asked Jul 17 at 20:46

Bak1139

1,39921128

share|cite|improve this question

share|cite|improve this question

edited Jul 17 at 21:43

edited Jul 17 at 21:43

edited Jul 17 at 21:43

asked Jul 17 at 20:46

Bak1139

1,39921128

asked Jul 17 at 20:46

Bak1139

1,39921128

asked Jul 17 at 20:46

Bak1139

1,39921128

1,39921128

closed as unclear what you're asking by m_t_, amWhy, Xander Henderson, Trần Thúc Minh Trí, max_zorn Jul 18 at 4:27

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

closed as unclear what you're asking by m_t_, amWhy, Xander Henderson, Trần Thúc Minh Trí, max_zorn Jul 18 at 4:27

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Probably the former, but maybe not "whenever". Edit the question to provide the context.
  – Ethan Bolker
  Jul 17 at 20:51
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  I have never seen that notation.
  – copper.hat
  Jul 17 at 20:51
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  How do we usually set the angle between the z axis and a vector? From the z unit vector counter clockwise ?
  – Bak1139
  Jul 17 at 20:53
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Probably the former, but maybe not "whenever". Edit the question to provide the context.
  – Ethan Bolker
  Jul 17 at 20:51
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  I have never seen that notation.
  – copper.hat
  Jul 17 at 20:51
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  How do we usually set the angle between the z axis and a vector? From the z unit vector counter clockwise ?
  – Bak1139
  Jul 17 at 20:53
  

  
  
  
  

1

1

Probably the former, but maybe not "whenever". Edit the question to provide the context.
– Ethan Bolker
Jul 17 at 20:51

Probably the former, but maybe not "whenever". Edit the question to provide the context.
– Ethan Bolker
Jul 17 at 20:51

1

1

I have never seen that notation.
– copper.hat
Jul 17 at 20:51

I have never seen that notation.
– copper.hat
Jul 17 at 20:51

How do we usually set the angle between the z axis and a vector? From the z unit vector counter clockwise ?
– Bak1139
Jul 17 at 20:53

How do we usually set the angle between the z axis and a vector? From the z unit vector counter clockwise ?
– Bak1139
Jul 17 at 20:53

add a comment | 

1 Answer
1

active

oldest

votes

up vote
1
down vote

It's both :)

I believe $(hattextbfn,z)$ stands for angle between unit vector $vecn$ and unit vector of $z$ axis, usually denoted with $vec k$.

So:

$$cos(hattextbfn,z)<0$$

...is equivalent to:

$$angle(vec n, vec k)>90^circ$$

...or:

$$vec ncdotvec k<0$$

share|cite|improve this answer

answered Jul 17 at 21:04

Oldboy

2,6101316

add a comment | 

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

active

oldest

votes

active

oldest

votes

up vote
1
down vote

It's both :)

I believe $(hattextbfn,z)$ stands for angle between unit vector $vecn$ and unit vector of $z$ axis, usually denoted with $vec k$.

So:

$$cos(hattextbfn,z)<0$$

...is equivalent to:

$$angle(vec n, vec k)>90^circ$$

...or:

$$vec ncdotvec k<0$$

share|cite|improve this answer

answered Jul 17 at 21:04

Oldboy

2,6101316

add a comment | 

up vote
1
down vote

It's both :)

I believe $(hattextbfn,z)$ stands for angle between unit vector $vecn$ and unit vector of $z$ axis, usually denoted with $vec k$.

So:

$$cos(hattextbfn,z)<0$$

...is equivalent to:

$$angle(vec n, vec k)>90^circ$$

...or:

$$vec ncdotvec k<0$$

share|cite|improve this answer

answered Jul 17 at 21:04

Oldboy

2,6101316

add a comment | 

up vote
1
down vote

up vote
1
down vote

It's both :)

I believe $(hattextbfn,z)$ stands for angle between unit vector $vecn$ and unit vector of $z$ axis, usually denoted with $vec k$.

So:

$$cos(hattextbfn,z)<0$$

...is equivalent to:

$$angle(vec n, vec k)>90^circ$$

...or:

$$vec ncdotvec k<0$$

share|cite|improve this answer

answered Jul 17 at 21:04

Oldboy

2,6101316

It's both :)

I believe $(hattextbfn,z)$ stands for angle between unit vector $vecn$ and unit vector of $z$ axis, usually denoted with $vec k$.

So:

$$cos(hattextbfn,z)<0$$

...is equivalent to:

$$angle(vec n, vec k)>90^circ$$

...or:

$$vec ncdotvec k<0$$

share|cite|improve this answer

answered Jul 17 at 21:04

Oldboy

2,6101316

share|cite|improve this answer

share|cite|improve this answer

answered Jul 17 at 21:04

Oldboy

2,6101316

answered Jul 17 at 21:04

Oldboy

2,6101316

answered Jul 17 at 21:04

Oldboy

2,6101316

2,6101316

add a comment | 

add a comment |