How to use inner product to find angle? Linear Algebra [on hold]











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Let C[0, π] denote the set of real-valued continuous functions on [0, π].
Define an inner product on C[0, π] by
(f, g)C[0,π] ≡ $$int_0^π f(x)g(x)dx$$.
Use this inner product to determine the angle between sin x and x.










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put on hold as off-topic by José Carlos Santos, Masacroso, 5xum, amWhy, Delta-u yesterday


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Let C[0, π] denote the set of real-valued continuous functions on [0, π].
Define an inner product on C[0, π] by
(f, g)C[0,π] ≡ $$int_0^π f(x)g(x)dx$$.
Use this inner product to determine the angle between sin x and x.










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New contributor




Zhe Tian is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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put on hold as off-topic by José Carlos Santos, Masacroso, 5xum, amWhy, Delta-u yesterday


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 improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – José Carlos Santos, Masacroso, 5xum, amWhy, Delta-u

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









  • 3




    Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
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    yesterday













up vote
0
down vote

favorite









up vote
0
down vote

favorite











Let C[0, π] denote the set of real-valued continuous functions on [0, π].
Define an inner product on C[0, π] by
(f, g)C[0,π] ≡ $$int_0^π f(x)g(x)dx$$.
Use this inner product to determine the angle between sin x and x.










share|cite|improve this question







New contributor




Zhe Tian is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











Let C[0, π] denote the set of real-valued continuous functions on [0, π].
Define an inner product on C[0, π] by
(f, g)C[0,π] ≡ $$int_0^π f(x)g(x)dx$$.
Use this inner product to determine the angle between sin x and x.







linear-algebra






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put on hold as off-topic by José Carlos Santos, Masacroso, 5xum, amWhy, Delta-u yesterday


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 improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – José Carlos Santos, Masacroso, 5xum, amWhy, Delta-u

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




put on hold as off-topic by José Carlos Santos, Masacroso, 5xum, amWhy, Delta-u yesterday


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 improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – José Carlos Santos, Masacroso, 5xum, amWhy, Delta-u

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








  • 3




    Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
    – José Carlos Santos
    yesterday














  • 3




    Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
    – José Carlos Santos
    yesterday








3




3




Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
– José Carlos Santos
yesterday




Welcome to MSE. It will be more likely that you will get an answer if you show us that you made an effort. This should be added to the question rather than in the comments.
– José Carlos Santos
yesterday










2 Answers
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You know that $$langle f,grangle = int_0^pi f(x)g(x),dx,$$ and the formula for the angle between two elements $u, v$ in an inner product space $V$ is given by $$costheta = {langle u, vrangleover|u||v|}.$$ Observe that if $u = sin(x)$ and $v = x$, then $$|u|^2 = {langle u,urangle} = {int_0^pisin^2(x),dx} = {pi/2},$$ $$|v|^2 = langle v, vrangle = int_0^pi x^2,dx = {pi^3over3}.$$ I leave it to you to compute the remainder of the parts and apply inverse cosine to determine the angle.






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    HINT



    Recall that



    $$costheta=frac{langle u,vrangle}{sqrt{langle u,urangle}cdotsqrt{langle v,vrangle}}$$






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      2 Answers
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      2 Answers
      2






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      active

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      active

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      up vote
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      You know that $$langle f,grangle = int_0^pi f(x)g(x),dx,$$ and the formula for the angle between two elements $u, v$ in an inner product space $V$ is given by $$costheta = {langle u, vrangleover|u||v|}.$$ Observe that if $u = sin(x)$ and $v = x$, then $$|u|^2 = {langle u,urangle} = {int_0^pisin^2(x),dx} = {pi/2},$$ $$|v|^2 = langle v, vrangle = int_0^pi x^2,dx = {pi^3over3}.$$ I leave it to you to compute the remainder of the parts and apply inverse cosine to determine the angle.






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        You know that $$langle f,grangle = int_0^pi f(x)g(x),dx,$$ and the formula for the angle between two elements $u, v$ in an inner product space $V$ is given by $$costheta = {langle u, vrangleover|u||v|}.$$ Observe that if $u = sin(x)$ and $v = x$, then $$|u|^2 = {langle u,urangle} = {int_0^pisin^2(x),dx} = {pi/2},$$ $$|v|^2 = langle v, vrangle = int_0^pi x^2,dx = {pi^3over3}.$$ I leave it to you to compute the remainder of the parts and apply inverse cosine to determine the angle.






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          up vote
          2
          down vote










          up vote
          2
          down vote









          You know that $$langle f,grangle = int_0^pi f(x)g(x),dx,$$ and the formula for the angle between two elements $u, v$ in an inner product space $V$ is given by $$costheta = {langle u, vrangleover|u||v|}.$$ Observe that if $u = sin(x)$ and $v = x$, then $$|u|^2 = {langle u,urangle} = {int_0^pisin^2(x),dx} = {pi/2},$$ $$|v|^2 = langle v, vrangle = int_0^pi x^2,dx = {pi^3over3}.$$ I leave it to you to compute the remainder of the parts and apply inverse cosine to determine the angle.






          share|cite|improve this answer














          You know that $$langle f,grangle = int_0^pi f(x)g(x),dx,$$ and the formula for the angle between two elements $u, v$ in an inner product space $V$ is given by $$costheta = {langle u, vrangleover|u||v|}.$$ Observe that if $u = sin(x)$ and $v = x$, then $$|u|^2 = {langle u,urangle} = {int_0^pisin^2(x),dx} = {pi/2},$$ $$|v|^2 = langle v, vrangle = int_0^pi x^2,dx = {pi^3over3}.$$ I leave it to you to compute the remainder of the parts and apply inverse cosine to determine the angle.







          share|cite|improve this answer














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          share|cite|improve this answer








          edited 17 hours ago

























          answered yesterday









          Decaf-Math

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          3,027825






















              up vote
              1
              down vote













              HINT



              Recall that



              $$costheta=frac{langle u,vrangle}{sqrt{langle u,urangle}cdotsqrt{langle v,vrangle}}$$






              share|cite|improve this answer

























                up vote
                1
                down vote













                HINT



                Recall that



                $$costheta=frac{langle u,vrangle}{sqrt{langle u,urangle}cdotsqrt{langle v,vrangle}}$$






                share|cite|improve this answer























                  up vote
                  1
                  down vote










                  up vote
                  1
                  down vote









                  HINT



                  Recall that



                  $$costheta=frac{langle u,vrangle}{sqrt{langle u,urangle}cdotsqrt{langle v,vrangle}}$$






                  share|cite|improve this answer












                  HINT



                  Recall that



                  $$costheta=frac{langle u,vrangle}{sqrt{langle u,urangle}cdotsqrt{langle v,vrangle}}$$







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered yesterday









                  gimusi

                  84.2k74292




                  84.2k74292















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