解答
2sin(x−30∘)=cos(x−60∘)
解答
x=60∘+180∘n
+1
弧度
x=3π+πn求解步骤
2sin(x−30∘)=cos(x−60∘)
使用三角恒等式改写
2sin(x−30∘)=cos(x−60∘)
使用三角恒等式改写
sin(x−30∘)
使用角差恒等式: sin(s−t)=sin(s)cos(t)−cos(s)sin(t)=sin(x)cos(30∘)−cos(x)sin(30∘)
化简 sin(x)cos(30∘)−cos(x)sin(30∘):23sin(x)−21cos(x)
sin(x)cos(30∘)−cos(x)sin(30∘)
化简 cos(30∘):23
cos(30∘)
使用以下普通恒等式:cos(30∘)=23
cos(x) 周期表(周期为 360∘n):
x030∘45∘60∘90∘120∘135∘150∘cos(x)12322210−21−22−23x180∘210∘225∘240∘270∘300∘315∘330∘cos(x)−1−23−22−210212223
=23=23sin(x)−sin(30∘)cos(x)
化简 sin(30∘):21
sin(30∘)
使用以下普通恒等式:sin(30∘)=21
sin(x) 周期表(周期为 360∘n"):
x030∘45∘60∘90∘120∘135∘150∘sin(x)02122231232221x180∘210∘225∘240∘270∘300∘315∘330∘sin(x)0−21−22−23−1−23−22−21
=21=23sin(x)−21cos(x)
=23sin(x)−21cos(x)
使用角差恒等式: cos(s−t)=cos(s)cos(t)+sin(s)sin(t)=cos(x)cos(60∘)+sin(x)sin(60∘)
化简 cos(x)cos(60∘)+sin(x)sin(60∘):21cos(x)+23sin(x)
cos(x)cos(60∘)+sin(x)sin(60∘)
化简 cos(60∘):21
cos(60∘)
使用以下普通恒等式:cos(60∘)=21
cos(x) 周期表(周期为 360∘n):
x030∘45∘60∘90∘120∘135∘150∘cos(x)12322210−21−22−23x180∘210∘225∘240∘270∘300∘315∘330∘cos(x)−1−23−22−210212223
=21=21cos(x)+sin(60∘)sin(x)
化简 sin(60∘):23
sin(60∘)
使用以下普通恒等式:sin(60∘)=23
sin(x) 周期表(周期为 360∘n"):
x030∘45∘60∘90∘120∘135∘150∘sin(x)02122231232221x180∘210∘225∘240∘270∘300∘315∘330∘sin(x)0−21−22−23−1−23−22−21
=23=21cos(x)+23sin(x)
=21cos(x)+23sin(x)
2(23sin(x)−21cos(x))=21cos(x)+23sin(x)
化简 2(23sin(x)−21cos(x)):3sin(x)−cos(x)
2(23sin(x)−21cos(x))
使用分配律: a(b−c)=ab−aca=2,b=23sin(x),c=21cos(x)=2⋅23sin(x)−2⋅21cos(x)
化简 2⋅23sin(x)−2⋅21cos(x):3sin(x)−cos(x)
2⋅23sin(x)−2⋅21cos(x)
2⋅23sin(x)=3sin(x)
2⋅23sin(x)
分式相乘: a⋅cb=ca⋅b=223sin(x)
约分:2=sin(x)3
2⋅21cos(x)=cos(x)
2⋅21cos(x)
分式相乘: a⋅cb=ca⋅b=21⋅2cos(x)
约分:2=cos(x)⋅1
乘以:cos(x)⋅1=cos(x)=cos(x)
=3sin(x)−cos(x)
=3sin(x)−cos(x)
3sin(x)−cos(x)=21cos(x)+23sin(x)
3sin(x)−cos(x)=21cos(x)+23sin(x)
两边减去 21cos(x)+23sin(x)3sin(x)−23cos(x)−23sin(x)=0
化简 3sin(x)−23cos(x)−23sin(x):23sin(x)−3cos(x)
3sin(x)−23cos(x)−23sin(x)
乘 23cos(x):23cos(x)
23cos(x)
分式相乘: a⋅cb=ca⋅b=23cos(x)
=3sin(x)−23cos(x)−23sin(x)
乘 23sin(x):23sin(x)
23sin(x)
分式相乘: a⋅cb=ca⋅b=23sin(x)
=3sin(x)−23cos(x)−23sin(x)
合并分式 −23cos(x)−23sin(x):2−3cos(x)−3sin(x)
使用法则 ca±cb=ca±b=2−3cos(x)−3sin(x)
=3sin(x)+2−3cos(x)−3sin(x)
将项转换为分式: 3sin(x)=23sin(x)2=23sin(x)⋅2+2−3cos(x)−3sin(x)
因为分母相等,所以合并分式: ca±cb=ca±b=23sin(x)⋅2−3cos(x)−3sin(x)
3sin(x)⋅2−3cos(x)−3sin(x)=3sin(x)−3cos(x)
3sin(x)⋅2−3cos(x)−3sin(x)
对同类项分组=23sin(x)−3cos(x)−3sin(x)
同类项相加:23sin(x)−3sin(x)=3sin(x)=3sin(x)−3cos(x)
=23sin(x)−3cos(x)
23sin(x)−3cos(x)=0
g(x)f(x)=0⇒f(x)=03sin(x)−3cos(x)=0
使用三角恒等式改写
3sin(x)−3cos(x)=0
在两边除以 cos(x),cos(x)=0cos(x)3sin(x)−3cos(x)=cos(x)0
化简cos(x)3sin(x)−3=0
使用基本三角恒等式: cos(x)sin(x)=tan(x)3tan(x)−3=0
3tan(x)−3=0
将 3到右边
3tan(x)−3=0
两边加上 33tan(x)−3+3=0+3
化简3tan(x)=3
3tan(x)=3
两边除以 3
3tan(x)=3
两边除以 333tan(x)=33
化简
33tan(x)=33
化简 33tan(x):tan(x)
33tan(x)
约分:3=tan(x)
化简 33:3
33
使用根式运算法则: 3=321=3213
使用指数法则: xbxa=xa−b32131=31−21=31−21
数字相减:1−21=21=321
使用根式运算法则: 321=3=3
tan(x)=3
tan(x)=3
tan(x)=3
tan(x)=3的通解
tan(x) 周期表(周期为 180∘n):
x030∘45∘60∘90∘120∘135∘150∘tan(x)03313±∞−3−1−33
x=60∘+180∘n
x=60∘+180∘n