若sin(α-π)=2cos(2π-α),求[sin(π-α)+5cos(2π-α)]/[3cos(π-α)-sin(-α)]的值

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若sin(α-π)=2cos(2π-α),求[sin(π-α)+5cos(2π-α)]/[3cos(π-α)-sin(-α)]的值若sin(α-π)=2cos(2π-α),求[sin(π-α)+5co

若sin(α-π)=2cos(2π-α),求[sin(π-α)+5cos(2π-α)]/[3cos(π-α)-sin(-α)]的值
若sin(α-π)=2cos(2π-α),求[sin(π-α)+5cos(2π-α)]/[3cos(π-α)-sin(-α)]的值

若sin(α-π)=2cos(2π-α),求[sin(π-α)+5cos(2π-α)]/[3cos(π-α)-sin(-α)]的值
用a代替
-sina=2cosa
sina=-2cosa
原式=(sina+5cosa)/(-3cosa+sina)
=(-2cosa+5cosa)/(-3cosa-2cosa)
=3cosa/(-5cosa)
=-3/5

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