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Calculus 3 - Vector Projections & Orthogonal Components

The Organic Chemistry Tutor · YouTube · 12:14

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Reviewed learning material · Video analysis · English
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Compute the parallel projection and perpendicular residual of a vector in two and three dimensions.

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Chapters

1:30Decompose relative to a vector4:30Compute the projection6:00Check the residual

Learning script

Generated from the video's visuals and explanation; not verbatim speech.

For a nonzero reference vector v, split u into a component parallel to v and another perpendicular to v. These directions are relative to v, not necessarily the coordinate axes.

For u=(3,5)u=(3,5) and v=(2,4)v=(2,4), the coefficient is (u⋅vu\cdot v)/(v⋅vv\cdot v)=26/20=13/1026/20=13/10. The projection is (13/513/5,26/526/5).

Subtracting the projection gives (2/52/5,−1/51/5). Its dot product with v is zero, confirming that the remaining component is orthogonal.

Knowledge cards

01

Decompose relative to a vector

For a nonzero reference vector v, split u into a component parallel to v and another perpendicular to v. These directions are relative to v, not necessarily the coordinate axes.

02

Compute the projection

For u=(3,5)u=(3,5) and v=(2,4)v=(2,4), the coefficient is (u⋅vu\cdot v)/(v⋅vv\cdot v)=26/20=13/1026/20=13/10. The projection is (13/513/5,26/526/5).

03

Check the residual

Subtracting the projection gives (2/52/5,−1/51/5). Its dot product with v is zero, confirming that the remaining component is orthogonal.

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  • Orthogonal projections ExplanationAt 1:30
    Why this connection?

    For a nonzero reference vector v, split u into a component parallel to v and another perpendicular to v. These directions are relative to v, not necessarily the coordinate axes. For u=(3,5)u=(3,5) and v=(2,4)v=(2,4), the coefficient is (u⋅vu\cdot v)/(v⋅vv\cdot v)=26/20=13/1026/20=13/10. The projection is (13/513/5,26/526/5). Subtracting the projection gives (2/52/5,−1/51/5). Its dot product with v is zero, confirming that the remaining component is orthogonal.