已知tana=2,求sina.sin(a-π/4)

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/25 14:27:15
已知tana=2,求sina.sin(a-π/4)
x){}KKmtml*Kt$o7y&H8v6$ TTi53 ABF`co 2$(Qd`r~q UADM0[bd~qAbԵ6`HѣY j[ . ĆRFF(<[c mhohd1>T

已知tana=2,求sina.sin(a-π/4)
已知tana=2,求sina.sin(a-π/4)

已知tana=2,求sina.sin(a-π/4)
tan(a-π/4) =(tana-1)/(tana+1) =(2-1)/(2+1) =1/3.sin^2a+sinacosa-2cos^2a =(sina+2cosa)(sina-cosa) =(2cosa+2cosa)(2cosa-

sina=2√5/5 sin(a-π/4)=sinacosπ/4-cosasinπ/4=2√5/5*√2/2-√5/5*√2/2=3√10/10