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Prove that the determinant `[xsinthetacostheta-sintheta-x1costheta1x]`is independent of 0. |
Answer» `[{:(x,"sin"theta,"cos"theta),("-sin"theta,-x,1),("cos"theta,1,x):}]` `[{:(-x,1),(1,x):}]"-sin"theta[{:("-sin"theta,1),("cos"theta,x):}]"+cos"theta|{:("-sin"theta,-x),("cos"theta,1):}|` `=x(-x^(2)-1)-"sin"theta(-x"sin"theta-"cos"theta)+"cos"theta(-"sin"theta"+x"cos"theta)` `=-x^(3)-x+x"sin"^(2)theta+"sin"theta"cos"theta-"sin"theta"cos"theta+x"cos"^(2)theta` `=-x^(3)-x+x(sin^(2)theta+cos^(2)theta)` `=-x^(3)-x+x=-x^(3)` |
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