trig

Multiply:
5(cos Pi/3 + i sin Pi/3)times 2 (cos Pi/4 + i sin Pi/4) and leave the answer in trigonometric notation.

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  1. Using the following result:
    (cosα+isinα)(cosβ+isinβ)
    =cosαcosβ-sinαsin&beta + i(sinαcosβ+cosαsinβ)
    =cos(α+β) + i sin(α+β)

    So
    5(cos Pi/3 + i sin Pi/3)times 2 (cos Pi/4 + i sin Pi/4)
    is simply
    5*2 (cos(π/3+π4)+i sin(π/3+π/4))
    =10(cos(7π/12)+i sin(7π/12))

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