王子变青蛙第9集视频:f1=sin(#t/3+#/4),f2=(根号3)sin(#t/3-#/4),求f1+f2=?
来源:百度文库 编辑:高考问答 时间:2024/05/15 11:45:54
要过程,在线等,最先给出正确过程的加分
#是表示圆周率pi吗?
f1 = sin(#t/3+#/4)
= 2(cos#/3 * sin(#t/3+#/4))
f2 = √3sin(#t/3-#/4)
= 2(sin#/3 * sin(#t/3-#/4))
= -2(sin#/3 * cos(#t/3+#/4))
f1+f2 = 2( cos#/3 * sin(#t/3+#/4) - sin#/3 * cos(#t/3+#/4) )
= 2sin(#t/3+#/4 - #/3)
= 2sin(#t/3-#/12)
易知sin(#t/3+#/4)=cos[#/2-(#t/3+#/4)]=cos(#/4-#t/3)
=cos(#t/3-#/4)
所以f1+f2=(根号3)sin(#t/3-#/4)+cos(#t/3-#/4)
=2sin(#t/3-#/4+#/6)=2sin(#t/3-#/12)
f1=sin(#t/3+#/4),f2=(根号3)sin(#t/3-#/4),求f1+f2=?
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