Sin20+sin40-sin80= a) -1 b) 1 c) 2 d) 0

Question

Sin20+sin40-sin80=
a) -1 b) 1 c) 2 d) 0

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Adalynn 2 weeks 2021-09-11T11:43:55+00:00 1 Answer 0 views 0

Answers ( )

    0
    2021-09-11T11:45:23+00:00

    2 \sin( \frac{20 + 40}{2} )  \cos( \frac{20 - 40}{2} )  -  \sin(80)

    =cos10- sin(90-10)

    =cos10- cos10

    =0

    so answer is zero

    D.

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