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受欢迎的 三角函数 >

cot(-pi/5)-sec(x)=1.5

  • 初等代数
  • 代数
  • 微积分入门
  • 微积分
  • 函数
  • 线性代数
  • 三角
  • 统计
  • 化学

解答

cot(−5π​)−sec(x)=1.5

解答

x=1.92586…+2πn,x=−1.92586…+2πn
+1
度数
x=110.34419…∘+360∘n,x=−110.34419…∘+360∘n
求解步骤
cot(−5π​)−sec(x)=1.5
cot(−5π​)=−20(310​+52​)5−5​​​
cot(−5π​)
利用以下特性:cot(−x)=−cot(x)cot(−5π​)=−cot(5π​)=−cot(5π​)
使用三角恒等式改写:cot(5π​)=20(310​+52​)5−5​​​
cot(5π​)
使用三角恒等式改写:sin(5π​)cos(5π​)​
cot(5π​)
使用基本三角恒等式: cot(x)=sin(x)cos(x)​=sin(5π​)cos(5π​)​
=sin(5π​)cos(5π​)​
使用三角恒等式改写:cos(5π​)=45​+1​
cos(5π​)
显示:cos(5π​)−sin(10π​)=21​
使用以下积化和差公式: 2sin(x)cos(y)=sin(x+y)−sin(x−y)2cos(5π​)sin(10π​)=sin(103π​)−sin(10π​)
显示:2cos(5π​)sin(10π​)=21​
使用倍角公式: sin(2x)=2sin(x)cos(x)sin(52π​)=2sin(5π​)cos(5π​)sin(52π​)sin(5π​)=4sin(5π​)sin(10π​)cos(5π​)cos(10π​)
两边除以 sin(5π​)sin(52π​)=4sin(10π​)cos(5π​)cos(10π​)
利用以下特性: sin(x)=cos(2π​−x)sin(52π​)=cos(2π​−52π​)cos(2π​−52π​)=4sin(10π​)cos(5π​)cos(10π​)
cos(10π​)=4sin(10π​)cos(5π​)cos(10π​)
两边除以 cos(10π​)1=4sin(10π​)cos(5π​)
两边除以 221​=2sin(10π​)cos(5π​)
代入 21​=2sin(10π​)cos(5π​)21​=sin(103π​)−sin(10π​)
sin(103π​)=cos(2π​−103π​)21​=cos(2π​−103π​)−sin(10π​)
21​=cos(5π​)−sin(10π​)
显示:cos(5π​)+sin(10π​)=45​​
使用因式分解法则:a2−b2=(a+b)(a−b)a=cos(5π​)+sin(10π​)(cos(5π​)+sin(10π​))2−(cos(5π​)−sin(10π​))2=((cos(5π​)+sin(10π​))+(cos(5π​)−sin(10π​)))((cos(5π​)+sin(10π​))−(cos(5π​)−sin(10π​)))
整理后得(cos(5π​)+sin(10π​))2−(cos(5π​)−sin(10π​))2=2(2cos(5π​)sin(10π​))
显示:2cos(5π​)sin(10π​)=21​
使用倍角公式: sin(2x)=2sin(x)cos(x)sin(52π​)=2sin(5π​)cos(5π​)sin(52π​)sin(5π​)=4sin(5π​)sin(10π​)cos(5π​)cos(10π​)
两边除以 sin(5π​)sin(52π​)=4sin(10π​)cos(5π​)cos(10π​)
利用以下特性: sin(x)=cos(2π​−x)sin(52π​)=cos(2π​−52π​)cos(2π​−52π​)=4sin(10π​)cos(5π​)cos(10π​)
cos(10π​)=4sin(10π​)cos(5π​)cos(10π​)
两边除以 cos(10π​)1=4sin(10π​)cos(5π​)
两边除以 221​=2sin(10π​)cos(5π​)
代入 2cos(5π​)sin(10π​)=21​(cos(5π​)+sin(10π​))2−(cos(5π​)−sin(10π​))2=1
代入 cos(5π​)−sin(10π​)=21​(cos(5π​)+sin(10π​))2−(21​)2=1
整理后得(cos(5π​)+sin(10π​))2−41​=1
两边加上 41​(cos(5π​)+sin(10π​))2−41​+41​=1+41​
整理后得(cos(5π​)+sin(10π​))2=45​
在两侧开平方cos(5π​)+sin(10π​)=±45​​
cos(5π​)不能为负sin(10π​)不能为负cos(5π​)+sin(10π​)=45​​
以下方程式相加cos(5π​)+sin(10π​)=25​​((cos(5π​)+sin(10π​))+(cos(5π​)−sin(10π​)))=(25​​+21​)
整理后得cos(5π​)=45​+1​
=45​+1​
使用三角恒等式改写:sin(5π​)=42​5−5​​​
sin(5π​)
显示:cos(5π​)−sin(10π​)=21​
使用以下积化和差公式: 2sin(x)cos(y)=sin(x+y)−sin(x−y)2cos(5π​)sin(10π​)=sin(103π​)−sin(10π​)
显示:2cos(5π​)sin(10π​)=21​
使用倍角公式: sin(2x)=2sin(x)cos(x)sin(52π​)=2sin(5π​)cos(5π​)sin(52π​)sin(5π​)=4sin(5π​)sin(10π​)cos(5π​)cos(10π​)
两边除以 sin(5π​)sin(52π​)=4sin(10π​)cos(5π​)cos(10π​)
利用以下特性: sin(x)=cos(2π​−x)sin(52π​)=cos(2π​−52π​)cos(2π​−52π​)=4sin(10π​)cos(5π​)cos(10π​)
cos(10π​)=4sin(10π​)cos(5π​)cos(10π​)
两边除以 cos(10π​)1=4sin(10π​)cos(5π​)
两边除以 221​=2sin(10π​)cos(5π​)
代入 21​=2sin(10π​)cos(5π​)21​=sin(103π​)−sin(10π​)
sin(103π​)=cos(2π​−103π​)21​=cos(2π​−103π​)−sin(10π​)
21​=cos(5π​)−sin(10π​)
显示:cos(5π​)+sin(10π​)=45​​
使用因式分解法则:a2−b2=(a+b)(a−b)a=cos(5π​)+sin(10π​)(cos(5π​)+sin(10π​))2−(cos(5π​)−sin(10π​))2=((cos(5π​)+sin(10π​))+(cos(5π​)−sin(10π​)))((cos(5π​)+sin(10π​))−(cos(5π​)−sin(10π​)))
整理后得(cos(5π​)+sin(10π​))2−(cos(5π​)−sin(10π​))2=2(2cos(5π​)sin(10π​))
显示:2cos(5π​)sin(10π​)=21​
使用倍角公式: sin(2x)=2sin(x)cos(x)sin(52π​)=2sin(5π​)cos(5π​)sin(52π​)sin(5π​)=4sin(5π​)sin(10π​)cos(5π​)cos(10π​)
两边除以 sin(5π​)sin(52π​)=4sin(10π​)cos(5π​)cos(10π​)
利用以下特性: sin(x)=cos(2π​−x)sin(52π​)=cos(2π​−52π​)cos(2π​−52π​)=4sin(10π​)cos(5π​)cos(10π​)
cos(10π​)=4sin(10π​)cos(5π​)cos(10π​)
两边除以 cos(10π​)1=4sin(10π​)cos(5π​)
两边除以 221​=2sin(10π​)cos(5π​)
代入 2cos(5π​)sin(10π​)=21​(cos(5π​)+sin(10π​))2−(cos(5π​)−sin(10π​))2=1
代入 cos(5π​)−sin(10π​)=21​(cos(5π​)+sin(10π​))2−(21​)2=1
整理后得(cos(5π​)+sin(10π​))2−41​=1
两边加上 41​(cos(5π​)+sin(10π​))2−41​+41​=1+41​
整理后得(cos(5π​)+sin(10π​))2=45​
在两侧开平方cos(5π​)+sin(10π​)=±45​​
cos(5π​)不能为负sin(10π​)不能为负cos(5π​)+sin(10π​)=45​​
以下方程式相加cos(5π​)+sin(10π​)=25​​((cos(5π​)+sin(10π​))+(cos(5π​)−sin(10π​)))=(25​​+21​)
整理后得cos(5π​)=45​+1​
两边进行平方(cos(5π​))2=(45​+1​)2
利用以下特性: sin2(x)=1−cos2(x)sin2(5π​)=1−cos2(5π​)
代入 cos(5π​)=45​+1​sin2(5π​)=1−(45​+1​)2
整理后得sin2(5π​)=85−5​​
在两侧开平方sin(5π​)=±85−5​​​
sin(5π​)不能为负sin(5π​)=85−5​​​
整理后得sin(5π​)=225−5​​​​
=225−5​​​​
225−5​​​​=42​5−5​​​
225−5​​​​
25−5​​​=2​5−5​​​
25−5​​​
使用根式运算法则: nba​​=nb​na​​, 假定 a≥0,b≥0=2​5−5​​​
=22​5−5​​​​
使用分式法则: acb​​=c⋅ab​=2​⋅25−5​​​
22​5−5​​​有理化:42​5−5​​​
22​5−5​​​
乘以共轭根式 2​2​​=2​⋅22​5−5​​2​​
2​⋅22​=4
2​⋅22​
使用指数法则: ab⋅ac=ab+c22​2​=2⋅221​⋅221​=21+21​+21​=21+21​+21​
同类项相加:21​+21​=2⋅21​=21+2⋅21​
2⋅21​=1
2⋅21​
分式相乘: a⋅cb​=ca⋅b​=21⋅2​
约分:2=1
=21+1
数字相加:1+1=2=22
22=4=4
=42​5−5​​​
=42​5−5​​​
=42​5−5​​​
=42​5−5​​​45​+1​​
化简 42​5−5​​​45​+1​​:20(310​+52​)5−5​​​
42​5−5​​​45​+1​​
分式相除: dc​ba​​=b⋅ca⋅d​=42​5−5​​(5​+1)⋅4​
约分:4=2​5−5​​5​+1​
2​5−5​​5​+1​有理化:20(310​+52​)5−5​​​
2​5−5​​5​+1​
乘以共轭根式 2​2​​=2​5−5​​2​(5​+1)2​​
2​5−5​​2​=25−5​​
2​5−5​​2​
使用根式运算法则: a​a​=a2​2​=2=25−5​​
=25−5​​2​(5​+1)​
乘以共轭根式 5−5​​5−5​​​=25−5​​5−5​​2​(5​+1)5−5​​​
25−5​​5−5​​=10−25​
25−5​​5−5​​
使用根式运算法则: a​a​=a5−5​​5−5​​=5−5​=2(5−5​)
使用分配律: a(b−c)=ab−aca=2,b=5,c=5​=2⋅5−25​
数字相乘:2⋅5=10=10−25​
=10−25​2​(5​+1)5−5​​​
因式分解出通项 −2:−2(5​−5)
−25​+10
将 10 改写为 2⋅5=−25​+2⋅5
因式分解出通项 −2=−2(5​−5)
=−2(5​−5)2​(5​+1)5−5​​​
消掉 −2(5​−5)2​(5​+1)5−5​​​:2(5−5​)2​(5​+1)5−5​​​
−2(5​−5)2​(5​+1)5−5​​​
5​−5=−(5−5​)=−−2(5−5​)2​(1+5​)5−5​​​
整理后得=2(5−5​)2​(5​+1)5−5​​​
=2(5−5​)2​(5​+1)5−5​​​
乘以共轭根式 5+5​5+5​​=2(5−5​)(5+5​)2​(5​+1)5−5​​(5+5​)​
2​(5​+1)5−5​​(5+5​)=610​5−5​​+102​5−5​​
2​(5​+1)5−5​​(5+5​)
=2​(5​+1)(5+5​)5−5​​
乘开 (5​+1)(5+5​):65​+10
(5​+1)(5+5​)
使用 FOIL 方法: (a+b)(c+d)=ac+ad+bc+bda=5​,b=1,c=5,d=5​=5​⋅5+5​5​+1⋅5+1⋅5​
=55​+5​5​+1⋅5+1⋅5​
化简 55​+5​5​+1⋅5+1⋅5​:65​+10
55​+5​5​+1⋅5+1⋅5​
同类项相加:55​+1⋅5​=65​=65​+5​5​+1⋅5
使用根式运算法则: a​a​=a5​5​=5=65​+5+1⋅5
数字相乘:1⋅5=5=65​+5+5
数字相加:5+5=10=65​+10
=65​+10
=2​5−5​​(65​+10)
乘开 2​5−5​​(65​+10):610​5−5​​+102​5−5​​
2​5−5​​(65​+10)
使用分配律: a(b+c)=ab+aca=2​5−5​​,b=65​,c=10=2​5−5​​⋅65​+2​5−5​​⋅10
=62​5​5−5​​+102​5−5​​
62​5​5−5​​=610​5−5​​
62​5​5−5​​
使用根式运算法则: a​b​=a⋅b​2​5​5−5​​=2⋅5(5−5​)​=62⋅5(5−5​)​
数字相乘:2⋅5=10=610(5−5​)​
使用根式运算法则: nab​=na​nb​, 假定 a≥0,b≥010(5−5​)​=10​5−5​​=610​5−5​​
=610​5−5​​+102​5−5​​
=610​5−5​​+102​5−5​​
2(5−5​)(5+5​)=40
2(5−5​)(5+5​)
乘开 (5−5​)(5+5​):20
(5−5​)(5+5​)
使用平方差公式: (a−b)(a+b)=a2−b2a=5,b=5​=52−(5​)2
化简 52−(5​)2:20
52−(5​)2
52=25
52
52=25=25
(5​)2=5
(5​)2
使用根式运算法则: a​=a21​=(521​)2
使用指数法则: (ab)c=abc=521​⋅2
21​⋅2=1
21​⋅2
分式相乘: a⋅cb​=ca⋅b​=21⋅2​
约分:2=1
=5
=25−5
数字相减:25−5=20=20
=20
=2⋅20
乘开 2⋅20:40
2⋅20
打开括号=2⋅20
数字相乘:2⋅20=40=40
=40
=40610​5−5​​+102​5−5​​​
分解 610​5−5​​+102​5−5​​:25−5​​(310​+52​)
610​5−5​​+102​5−5​​
改写为=3⋅25−5​​10​+5⋅25−5​​2​
因式分解出通项 25−5​​=25−5​​(310​+52​)
=4025−5​​(310​+52​)​
约分:2=20(310​+52​)5−5​​​
=20(310​+52​)5−5​​​
=20(310​+52​)5−5​​​
=−20(310​+52​)5−5​​​
−20(310​+52​)5−5​​​−sec(x)=1.5
将 20(310​+52​)5−5​​​到右边
−20(310​+52​)5−5​​​−sec(x)=1.5
两边加上 20(310​+52​)5−5​​​−20(310​+52​)5−5​​​−sec(x)+20(310​+52​)5−5​​​=1.5+20(310​+52​)5−5​​​
化简
−20(310​+52​)5−5​​​−sec(x)+20(310​+52​)5−5​​​=1.5+20(310​+52​)5−5​​​
化简 −20(310​+52​)5−5​​​−sec(x)+20(310​+52​)5−5​​​:−sec(x)
−20(310​+52​)5−5​​​−sec(x)+20(310​+52​)5−5​​​
同类项相加:−20(310​+52​)5−5​​​+20(310​+52​)5−5​​​=0
=−sec(x)
化简 1.5+20(310​+52​)5−5​​​:2.87638…
1.5+20(310​+52​)5−5​​​
20(310​+52​)5−5​​​=2016.55790…5−5​​​
20(310​+52​)5−5​​​
310​=9.48683…
310​
转换为小数形式10​=3.16227…=3⋅3.16227…
数字相乘:3⋅3.16227…=9.48683…=9.48683…
52​=7.07106…
52​
转换为小数形式2​=1.41421…=5⋅1.41421…
数字相乘:5⋅1.41421…=7.07106…=7.07106…
=20(7.07106…+9.48683…)5−5​​​
数字相加:9.48683…+7.07106…=16.55790…=2016.55790…5−5​​​
=1.5+2016.55790…5−5​​​
2016.55790…5−5​​​=1.37638…
2016.55790…5−5​​​
转换为小数形式5−5​​=1.66250…=201.66250…⋅16.55790…​
数字相乘:16.55790…⋅1.66250…=27.52763…=2027.52763…​
数字相除:2027.52763…​=1.37638…=1.37638…
=1.5+1.37638…
数字相加:1.5+1.37638…=2.87638…=2.87638…
−sec(x)=2.87638…
−sec(x)=2.87638…
−sec(x)=2.87638…
两边除以 −1
−sec(x)=2.87638…
两边除以 −1−1−sec(x)​=−12.87638…​
化简sec(x)=−2.87638…
sec(x)=−2.87638…
使用反三角函数性质
sec(x)=−2.87638…
sec(x)=−2.87638…的通解sec(x)=−a⇒x=arcsec(−a)+2πn,x=−arcsec(−a)+2πnx=arcsec(−2.87638…)+2πn,x=−arcsec(−2.87638…)+2πn
x=arcsec(−2.87638…)+2πn,x=−arcsec(−2.87638…)+2πn
以小数形式表示解x=1.92586…+2πn,x=−1.92586…+2πn

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1/(cos^2(x))+(1/(2cos(x)))=0cos2(x)1​+(2cos(x)1​)=0cos(α)=sqrt((1+1/5)/2)cos(α)=21+51​​​(tan(x))(sin^2(x)-a)(sec(x)-a)=0,0<a<1(tan(x))(sin2(x)−a)(sec(x)−a)=0,0<a<1sin(pi/2 (x+1))= 2/5sin(2π​(x+1))=52​sin(*+pi/2)=cos(x)sin(⋅+2π​)=cos(x)
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