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Simplify, cosθ[cosθsinθ-sinθcosθ]+sinθ[sinθ-cosθcosθsinθ] - Mathematics and Statistics

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Question

Simplify, `costheta[(costheta, sintheta),(-sintheta, costheta)] + sintheta[(sintheta, -costheta),(costheta, sintheta)]`

Sum

Solution

`costheta[(costheta, sintheta),(-sintheta, costheta)] + sintheta[(sintheta, -costheta),(costheta, sintheta)]`

= `[(cos^2theta, costheta sintheta),(-costheta sintheta, cos^2theta)] + [(sin^2theta, -costheta sintheta),(costhetasintheta, sin^2theta)]`

= `[(cos^2theta + sin^2theta ,costhetasintheta - costhetasintheta),(-costhetasintheta + costhetasintheta, cos^2theta + sin^2theta)]`

= `[(1, 0),(0, 1)]`

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Chapter 4: Determinants and Matrices - Exercise 4.5 [Page 87]

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