解答
求解 y,sin(x+y)+sin(y+z)+sin(x+z)=0
解答
y=arcsin(−2cos(2x−z)sin(x+z))+2πn−2x−2z,y=π+arcsin(2cos(2x−z)sin(x+z))+2πn−2x−2z
求解步骤
sin(x+y)+sin(y+z)+sin(x+z)=0
使用三角恒等式改写
sin(x+y)+sin(y+z)+sin(x+z)
使用和差化积恒等式: sin(s)+sin(t)=2sin(2s+t)cos(2s−t)=sin(x+z)+2sin(2x+y+y+z)cos(2x+y−(y+z))
2sin(2x+y+y+z)cos(2x+y−(y+z))=2cos(2x−z)sin(2x+2y+z)
2sin(2x+y+y+z)cos(2x+y−(y+z))
同类项相加:y+y=2y=2sin(22y+x+z)cos(2y+x−(y+z))
乘开 x+y−(y+z):x−z
x+y−(y+z)
−(y+z):−y−z
−(y+z)
打开括号=−y−z
使用加减运算法则+(−a)=−a=−y−z
=x+y−y−z
同类项相加:y−y=0=x−z
=2cos(2x−z)sin(22y+x+z)
=sin(x+z)+2cos(2x−z)sin(2x+2y+z)
sin(x+z)+2cos(2x−z)sin(2x+2y+z)=0
将 sin(x+z)到右边
sin(x+z)+2cos(2x−z)sin(2x+2y+z)=0
两边减去 sin(x+z)sin(x+z)+2cos(2x−z)sin(2x+2y+z)−sin(x+z)=0−sin(x+z)
化简2cos(2x−z)sin(2x+2y+z)=−sin(x+z)
2cos(2x−z)sin(2x+2y+z)=−sin(x+z)
两边除以 2cos(2x−z);x=π+4πn+z,x=3π+4πn+z
2cos(2x−z)sin(2x+2y+z)=−sin(x+z)
两边除以 2cos(2x−z);x=π+4πn+z,x=3π+4πn+z2cos(2x−z)2cos(2x−z)sin(2x+2y+z)=2cos(2x−z)−sin(x+z);x=π+4πn+z,x=3π+4πn+z
化简sin(2x+2y+z)=−2cos(2x−z)sin(x+z);x=π+4πn+z,x=3π+4πn+z
sin(2x+2y+z)=−2cos(2x−z)sin(x+z);x=π+4πn+z,x=3π+4πn+z
使用反三角函数性质
sin(2x+2y+z)=−2cos(2x−z)sin(x+z)
sin(2x+2y+z)=−2cos(2x−z)sin(x+z)的通解sin(x)=a⇒x=arcsin(a)+2πn,x=π+arcsin(a)+2πn2x+2y+z=arcsin(−2cos(2x−z)sin(x+z))+2πn,2x+2y+z=π+arcsin(2cos(2x−z)sin(x+z))+2πn
2x+2y+z=arcsin(−2cos(2x−z)sin(x+z))+2πn,2x+2y+z=π+arcsin(2cos(2x−z)sin(x+z))+2πn
解 2x+2y+z=arcsin(−2cos(2x−z)sin(x+z))+2πn:y=arcsin(−2cos(2x−z)sin(x+z))+2πn−2x−2z
2x+2y+z=arcsin(−2cos(2x−z)sin(x+z))+2πn
在两边乘以 2
2x+2y+z=arcsin(−2cos(2x−z)sin(x+z))+2πn
在两边乘以 222(x+2y+z)=2arcsin(−2cos(2x−z)sin(x+z))+2⋅2πn
化简
22(x+2y+z)=2arcsin(−2cos(2x−z)sin(x+z))+2⋅2πn
化简 22(x+2y+z):x+2y+z
22(x+2y+z)
数字相除:22=1=x+2y+z
化简 2arcsin(−2cos(2x−z)sin(x+z))+2⋅2πn:2arcsin(−2cos(2x−z)sin(x+z))+4πn
2arcsin(−2cos(2x−z)sin(x+z))+2⋅2πn
数字相乘:2⋅2=4=2arcsin(−2cos(2x−z)sin(x+z))+4πn
x+2y+z=2arcsin(−2cos(2x−z)sin(x+z))+4πn
x+2y+z=2arcsin(−2cos(2x−z)sin(x+z))+4πn
x+2y+z=2arcsin(−2cos(2x−z)sin(x+z))+4πn
将 x到右边
x+2y+z=2arcsin(−2cos(2x−z)sin(x+z))+4πn
两边减去 xx+2y+z−x=2arcsin(−2cos(2x−z)sin(x+z))+4πn−x
化简2y+z=2arcsin(−2cos(2x−z)sin(x+z))+4πn−x
2y+z=2arcsin(−2cos(2x−z)sin(x+z))+4πn−x
将 z到右边
2y+z=2arcsin(−2cos(2x−z)sin(x+z))+4πn−x
两边减去 z2y+z−z=2arcsin(−2cos(2x−z)sin(x+z))+4πn−x−z
化简2y=2arcsin(−2cos(2x−z)sin(x+z))+4πn−x−z
2y=2arcsin(−2cos(2x−z)sin(x+z))+4πn−x−z
两边除以 2
2y=2arcsin(−2cos(2x−z)sin(x+z))+4πn−x−z
两边除以 222y=22arcsin(−2cos(2x−z)sin(x+z))+24πn−2x−2z
化简
22y=22arcsin(−2cos(2x−z)sin(x+z))+24πn−2x−2z
化简 22y:y
22y
数字相除:22=1=y
化简 22arcsin(−2cos(2x−z)sin(x+z))+24πn−2x−2z:arcsin(−2cos(2x−z)sin(x+z))+2πn−2x−2z
22arcsin(−2cos(2x−z)sin(x+z))+24πn−2x−2z
数字相除:22=1=arcsin(−2cos(2x−z)sin(x+z))+24πn−2x−2z
数字相除:24=2=arcsin(−2cos(2x−z)sin(x+z))+2πn−2x−2z
y=arcsin(−2cos(2x−z)sin(x+z))+2πn−2x−2z
y=arcsin(−2cos(2x−z)sin(x+z))+2πn−2x−2z
y=arcsin(−2cos(2x−z)sin(x+z))+2πn−2x−2z
解 2x+2y+z=π+arcsin(2cos(2x−z)sin(x+z))+2πn:y=π+arcsin(2cos(2x−z)sin(x+z))+2πn−2x−2z
2x+2y+z=π+arcsin(2cos(2x−z)sin(x+z))+2πn
在两边乘以 2
2x+2y+z=π+arcsin(2cos(2x−z)sin(x+z))+2πn
在两边乘以 222(x+2y+z)=2π+2arcsin(2cos(2x−z)sin(x+z))+2⋅2πn
化简
22(x+2y+z)=2π+2arcsin(2cos(2x−z)sin(x+z))+2⋅2πn
化简 22(x+2y+z):x+2y+z
22(x+2y+z)
数字相除:22=1=x+2y+z
化简 2π+2arcsin(2cos(2x−z)sin(x+z))+2⋅2πn:2π+2arcsin(2cos(2x−z)sin(x+z))+4πn
2π+2arcsin(2cos(2x−z)sin(x+z))+2⋅2πn
数字相乘:2⋅2=4=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn
x+2y+z=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn
x+2y+z=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn
x+2y+z=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn
将 x到右边
x+2y+z=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn
两边减去 xx+2y+z−x=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn−x
化简2y+z=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn−x
2y+z=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn−x
将 z到右边
2y+z=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn−x
两边减去 z2y+z−z=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn−x−z
化简2y=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn−x−z
2y=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn−x−z
两边除以 2
2y=2π+2arcsin(2cos(2x−z)sin(x+z))+4πn−x−z
两边除以 222y=22π+22arcsin(2cos(2x−z)sin(x+z))+24πn−2x−2z
化简
22y=22π+22arcsin(2cos(2x−z)sin(x+z))+24πn−2x−2z
化简 22y:y
22y
数字相除:22=1=y
化简 22π+22arcsin(2cos(2x−z)sin(x+z))+24πn−2x−2z:π+arcsin(2cos(2x−z)sin(x+z))+2πn−2x−2z
22π+22arcsin(2cos(2x−z)sin(x+z))+24πn−2x−2z
数字相除:22=1=π+arcsin(2cos(2x−z)sin(x+z))+24πn−2x−2z
数字相除:24=2=π+arcsin(2cos(2x−z)sin(x+z))+2πn−2x−2z
y=π+arcsin(2cos(2x−z)sin(x+z))+2πn−2x−2z
y=π+arcsin(2cos(2x−z)sin(x+z))+2πn−2x−2z
y=π+arcsin(2cos(2x−z)sin(x+z))+2πn−2x−2z
y=arcsin(−2cos(2x−z)sin(x+z))+2πn−2x−2z,y=π+arcsin(2cos(2x−z)sin(x+z))+2πn−2x−2z