若sin(α-360°)-cos(180°-α)=m,则sin(180°+α)·cos(180°-α)等于

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若sin(α-360°)-cos(180°-α)=m,则sin(180°+α)·cos(180°-α)等于若sin(α-360°)-cos(180°-α)=m,则sin(180°+α)·cos(180

若sin(α-360°)-cos(180°-α)=m,则sin(180°+α)·cos(180°-α)等于
若sin(α-360°)-cos(180°-α)=m,则sin(180°+α)·cos(180°-α)等于

若sin(α-360°)-cos(180°-α)=m,则sin(180°+α)·cos(180°-α)等于
sin(α-360°)-cos(180°-α)=m
所以sinα+cosα=m
平方
sin²α+cos²α+2sinαcosα=m²
1+2sinαcosα=m²
sinαcosα=(m²-1)/2
sin(180°+α)·cos(180°-α)
=-sinα·(-cosα)
=(m²-1)/2


sin(α-360°)-cos(180°-α)=m
sina+cosa=m....(1)
sin^2a+cos^2a=1..(2)
(1)^2-(2)有2sinacosa=m^2-1
sinacosa=(m^2-1)/2
sin(180°+α)·cos(180°-α)
=-sina*(-cosa)
=sinacosa
= (m^2-1)/2