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Exercise 6

Avg difficulty 2.5

Suppose that v1=[103],v2=[222]\vvec_1=\threevec103,\hspace{24pt} \vvec_2=\threevec222 form the basis for a plane WW in R3\real^3.

  1. Find a basis for the line that is the orthogonal complement W⊥W^\perp.

  2. Given the vector b=[6−62]\bvec=\threevec6{-6}2, find y\yvec, the orthogonal projection of b\bvec onto the line W⊥W^\perp.

  3. Explain why the vector z=b−y\zvec = \bvec-\yvec must be in WW and write z\zvec as a linear combination of v1\vvec_1 and v2\vvec_2.

Austin, Understanding Linear Algebra, §6.3 Orthogonal bases and projections, Exercise 6

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Adapted from Understanding Linear Algebra © 2023 David Austin. Licensed under CC BY 4.0. Source: Understanding Linear Algebra. Imported at revision 3e6dced.