三角函数是数学中属于初等函数中的超越函数的一类函数。它们的本质是任意角的集合与一个比值的集合的变量之间的映射。通常的三角函数是在平面直角坐标系中定义的，其定义域为整个实数域。另一种定义是在直角三角形中，但并不完全。

中文名

三角函数定律

外文名

trigonometric function

提出者提出时间

公元前1世纪

适用领域

几何学，代数学

应用学科

数学

三角函数值数值表

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语音

角α0°30°45°60°90°120°135°150°180°270°360°

弧度制oπ/6π/4π/3π/22π/33π/45π/6π3π/22π

sinαo1/2√2/2√3/21√3/2√2/21/20-10

cosα1√3/2√2/21/20-1/2-√2/2-√3/2-101

tanαo√3/31√3--√3-1-√3/30-0

下面的数值, 只有角度的经过订正, 数值的未验证

sin0=sin0°=0

cos0=cos0°=1

tan0=tan0°=0sin15=0.650；

sin15°=0.259

cos15=-0.759；cos15°=0.966

tan15=-0.855；tan15°=0.268

sin30°=1/2

cos30°=0.866；

tan30°=0.577；

sin45°=0.707；

cos45°=0.707

tan45=1.620；tan45°=1

sin60=-0.305；sin60°=0.866

cos60=-0.952；cos60°=1/2

tan60=0.320；tan60°=1.732

sin75=-0.388；sin75°=0.966

cos75=0.922；cos75°=0.259

tan75=-0.421；tan75°=sin75°/cos75° =3.732

sin90=0.894；sin90°=cos0°=1

cos90=-0.448；cos90°=sin0°=0

tan90=-1.995；tan90°不存在

sin105=-0.971；sin105°=cos15°

cos105=-0.241；cos105°=-sin15°

tan105=4.028；tan105°=-cot15°

sin120=0.581；sin120°=cos30°

cos120=0.814；cos120°=-sin30°

tan120=0.713；tan120°=-tan60°

sin135=0.088；sin135°=sin45°

cos135=-0.996；cos135°=-cos45°

tan135=-0.0887；tan135°=-tan45°

sin150=-0.7149；sin150°=sin30°

cos150=-0.699；cos150°=-cos30°

tan150=-1.022；tan150°=-tan30°

sin165=0.998；sin165°=sin15°

cos165=-0.066；cos165°=-cos15°

tan165=-15.041；tan165°=-tan15°

sin180=-0.801；sin180°=sin0°=0

cos180=-0.598；cos180°=-cos0°=-1

tan180=1.339；tan180°=0

sin195=0.219；sin195°=-sin15°

cos195=0.976；cos195°=-cos15°

tan195=0.225；tan195°=tan15°

sin360=0.959；sin360°=sin0°=0

cos360=-0.284；cos360°=cos0°=1

tan360=-3.380；tan360°=tan0°=0

cos72度=[(√5)-1]/4(利用黄金等腰三角形可得出)

sin1=0.01745240643728351 sin2=0.03489949670250097 sin3=0.05233595624294383

sin4=0.0697564737441253 sin5=0.08715574274765816 sin6=0.10452846326765346

sin7=0.12186934340514747 sin8=0.13917310096006544 sin9=0.15643446504023087

sin10=0.17364817766693033 sin11=0.1908089953765448 sin12=0.20791169081775931

sin13=0.22495105434386497 sin14=0.24192189559966773 sin15=0.25881904510252074

sin16=0.27563735581699916 sin17=0.2923717047227367 sin18=0.3090169943749474

sin19=0.3255681544571567 sin20=0.3420201433256687 sin21=0.35836794954530027

sin22=0.374606593415912 sin23=0.3907311284892737 sin24=0.40673664307580015

sin25=0.42261826174069944 sin26=0.4383711467890774 sin27=0.45399049973954675

sin28=0.4694715627858908 sin29=0.48480962024633706 sin30=0.49999999999999994

sin31=0.5150380749100542 sin32=0.5299192642332049 sin33=0.544639035015027

sin34=0.5591929034707468 sin35=0.573576436351046 sin36=0.5877852522924731

sin37=0.6018150231520483 sin38=0.6156614753256583 sin39=0.6293203910498375

sin40=0.6427876096865392 sin41=0.6560590289905073 sin42=0.6691306063588582

sin43=0.6819983600624985 sin44=0.6946583704589972 sin45=0.7071067811865475

sin46=0.7193398003386511 sin47=0.7313537016191705 sin48=0.7431448254773941

sin49=0.7547095802227719 sin50=0.766044443118978 sin51=0.7771459614569708

sin52=0.7880107536067219 sin53=0.7986355100472928 sin54=0.8090169943749474

sin55=0.8191520442889918 sin56=0.8290375725550417 sin57=0.8386705679454239

sin58=0.848048096156426 sin59=0.8571673007021122 sin60=0.8660254037844386

sin61=0.8746197071393957 sin62=0.8829475928589269 sin63=0.8910065241883678

sin64=0.898794046299167 sin65=0.9063077870366499 sin66=0.9135454576426009

sin67=0.9205048534524404 sin68=0.9271838545667873 sin69=0.9335804264972017

sin70=0.9396926207859083 sin71=0.9455185755993167 sin72=0.9510565162951535

sin73=0.9563047559630354 sin74=0.9612616959383189 sin75=0.9659258262890683

sin76=0.9702957262759965 sin77=0.9743700647852352 sin78=0.9781476007338057

sin79=0.981627183447664 sin80=0.984807753012208 sin81=0.9876883405951378

sin82=0.9902680687415704 sin83=0.992546151641322 sin84=0.9945218953682733

sin85=0.9961946980917455 sin86=0.9975640502598242 sin87=0.9986295347545738

sin88=0.9993908270190958 sin89=0.9998476951563913

sin90=1

cos1=0.9998476951563913 cos2=0.9993908270190958 cos3=0.9986295347545738

cos4=0.9975640502598242 cos5=0.9961946980917455 cos6=0.9945218953682733

cos7=0.992546151641322 cos8=0.9902680687415704 cos9=0.9876883405951378

cos10=0.984807753012208 cos11=0.981627183447664 cos12=0.9781476007338057

cos13=0.9743700647852352 cos14=0.9702957262759965 cos15=0.9659258262890683

cos16=0.9612616959383189 cos17=0.9563047559630355 cos18=0.9510565162951535

cos19=0.9455185755993168 cos20=0.9396926207859084 cos21=0.9335804264972017

cos22=0.9271838545667874 cos23=0.9205048534524404 cos24=0.9135454576426009

cos25=0.9063077870366499 cos26=0.898794046299167 cos27=0.8910065241883679

cos28=0.882947592858927 cos29=0.8746197071393957 cos30=0.8660254037844387

cos31=0.8571673007021123 cos32=0.848048096156426 cos33=0.838670567945424

cos34=0.8290375725550417 cos35=0.8191520442889918 cos36=0.8090169943749474

cos37=0.7986355100472928 cos38=0.7880107536067219 cos39=0.7771459614569709

cos40=0.766044443118978 cos41=0.754709580222772 cos42=0.7431448254773942

cos43=0.7313537016191705 cos44=0.7193398003386512 cos45=0.7071067811865476

cos46=0.6946583704589974 cos47=0.6819983600624985 cos48=0.6691306063588582

cos49=0.6560590289905074 cos50=0.6427876096865394 cos51=0.6293203910498375

cos52=0.6156614753256583 cos53=0.6018150231520484 cos54=0.5877852522924731

cos55=0.5735764363510462 cos56=0.5591929034707468 cos57=0.5446390350150272

cos58=0.5299192642332049 cos59=0.5150380749100544 cos60=0.5000000000000001

cos61=0.4848096202463371 cos62=0.46947156278589086 cos63=0.4539904997395468

cos64=0.43837114678907746 cos65=0.42261826174069944 cos66=0.4067366430758004

cos67=0.3907311284892737 cos68=0.3746065934159122 cos69=0.35836794954530015

cos70=0.3420201433256688 cos71=0.32556815445715675 cos72=0.30901699437494745

cos73=0.29237170472273677 cos74=0.27563735581699916 cos75=0.25881904510252074

cos76=0.24192189559966767 cos77=0.22495105434386514 cos78=0.20791169081775923

cos79=0.19080899537654491 cos80=0.17364817766693041 cos81=0.15643446504023092

cos82=0.13917310096006546 cos83=0.12186934340514749 cos84=0.10452846326765346

cos85=0.08715574274765836 cos86=0.06975647374412523 cos87=0.052335956242943966

cos88=0.03489949670250108 cos89=0.0174524064372836

tan1=0.017455064928217585 tan2=0.03492076949174773 tan3=0.052407779283041196

tan4=0.06992681194351041 tan5=0.08748866352592401 tan6=0.10510423526567646

tan7=0.1227845609029046 tan8=0.14054083470239145 tan9=0.15838444032453627

tan10=0.17632698070846497 tan11=0.19438030913771848 tan12=0.2125565616700221

tan13=0.2308681911255631 tan14=0.24932800284318068 tan15=0.2679491924311227

tan16=0.2867453857588079 tan17=0.30573068145866033 tan18=0.3249196962329063

tan19=0.34432761328966527 tan20=0.36397023426620234 tan21=0.3838640350354158

tan22=0.4040262258351568 tan23=0.4244748162096047 tan24=0.4452286853085361

tan25=0.4663076581549986 tan26=0.4877325885658614 tan27=0.5095254494944288

tan28=0.5317094316614788 tan29=0.554309051452769 tan30=0.5773502691896257

tan31=0.6008606190275604 tan32=0.6248693519093275 tan33=0.6494075931975104

tan34=0.6745085168424265 tan35=0.7002075382097097 tan36=0.7265425280053609

tan37=0.7535540501027942 tan38=0.7812856265067174 tan39=0.8097840331950072

tan40=0.8390996311772799 tan41=0.8692867378162267 tan42=0.9004040442978399

tan43=0.9325150861376618 tan44=0.9656887748070739 tan45=0.9999999999999999

tan46=1.0355303137905693 tan47=1.0723687100246826 tan48=1.1106125148291927

tan49=1.1503684072210092 tan50=1.19175359259421 tan51=1.234897156535051

tan52=1.2799416321930785 tan53=1.3270448216204098 tan54=1.3763819204711733

tan55=1.4281480067421144 tan56=1.4825609685127403 tan57=1.5398649638145827

tan58=1.6003345290410506 tan59=1.6642794823505173 tan60=1.7320508075688767

tan61=1.8040477552714235 tan62=1.8807264653463318 tan63=1.9626105055051503

tan64=2.050303841579296 tan65=2.1445069205095586 tan66=2.246036773904215

tan67=2.355852365823753 tan68=2.4750868534162946 tan69=2.6050890646938023

tan70=2.7474774194546216 tan71=2.904210877675822 tan72=3.0776835371752526

tan73=3.2708526184841404 tan74=3.4874144438409087 tan75=3.7320508075688776

tan76=4.0107809335358455 tan77=4.331475874284153 tan78=4.704630109478456

tan79=5.144554015970307 tan80=5.671281819617707 tan81=6.313751514675041

tan82=7.115369722384207 tan83=8.144346427974593 tan84=9.514364454222587

tan85=11.43005230276132 tan86=14.300666256711942 tan87=19.08113668772816

tan88=28.636253282915515 tan89=57.289961630759144

tan90=无取值范围

三角函数值数学方程式

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数关系

tanα ·cotα=1

sinα ·cscα=1

cosα ·secα=1

商的关系

tanα=sinα/cosα cotα=cosα/sinα

平方关系

以下关系，函数名不变，符号看象限.

sin(2kπ+α)=sinα

cos(2kπ+α)=cosα

tan(2kπ+α)=tanα

cot(2kπ+α)=cotα

sin(π+α)=-sinα

cos(π+α)=-cosα

tan(π+α)=tanα

cot(π+α)=cotα

sin(π－α)=sinα

cos(π－α)=-cosα

tan(π－α)=-tanα

cot(π－α)=-cotα

sin(2π－α)=-sinα

cos(2π－α)=cosα

tan(2π－α)=-tanα

cot(2π－α)=-cotα

以下关系，奇变偶不变，符号看象限

sin(90°-α)=cosα

cos(90°-α)=sinα

tan(90°-α)=cotα

cot(90°-α)=tanα

sin(90°+α)=cosα

cos(90°+α)=-sinα

tan(90°+α)=-cotα

cot(90°+α)=-tanα

sin(270°-α)=-cosα

cos(270°-α)=-sinα

tan(270°-α)=cotα

cot(270°-α)=tanα

sin(270°+α)=－cosα

cos(270°+α)=sinα

tan(270°+α)=-cotα

cot(270°+α)=-tanα

积化和差公式

sinα ·cosβ=(1/2)*[sin(α+β)+sin(α－β)]

cosα ·sinβ=(1/2)*[sin(α+β)－sin(α－β)]

cosα ·cosβ=(1/2)*[cos(α+β)+cos(α－β)]

sinα ·sinβ=-(1/2)*[cos(α+β)－cos(α－β)]

和差化积公式

sinα+sinβ=2sin[(α+β)/2]·cos[(α-β)/2]

sinα-sinβ=2cos[(α+β)/2]·sin[(α-β)/2]

cosα+cosβ=2cos[(α+β)/2]·cos[(α-β)/2]

cosα-cosβ=-2sin[(α+β)/2]·sin[(α-β)/2]

三倍角公式

sin3α=3sinα-4sin^3α;

cos3α=4cos^3α-3cosα

两角和与差的三角函数关系

sin(α+β)=sinαcosβ+cosαsinβ

sin(α-β)=sinαcosβ-cosαsinβ

cos(α+β)=cosαcosβ-sinαsinβ

cos(α-β)=cosαcosβ+sinαsinβ

tan(α+β)=(tanα+tanβ )/(1－tanα ·tanβ)

tan(α－β)=(tanα-tanβ )/(1+tanα ·tanβ)

正弦二倍角公式

sin2α = 2cosαsinα

推导：sin2A=sin(A+A)=sinAcosA+cosAsinA=2sinAcosA

拓展公式：sin2A=2sinAcosA=2tanAcos^2A=2tanA/[1+tan2A]

1+sin2A=(sinA+cosA)^2

余弦二倍角公式

余弦二倍角公式有三组表示形式，三组形式等价：

1.Cos2a=Cos^2a-Sin^2a=[1-tan2a]/[1+tan2a]

2.Cos2a=1-2Sin^2a

3.Cos2a=2Cos^2a-1

推导：cos2A=cos(A+A)=cosAcosA-sinAsinA=cos^2A-sin^2A=2cos^2A-1

=1-2sin^2A

正切二倍角公式

tan2α=2tanα/[1-tan2α]

推导：tan2A=tan(A+A)=(tanA+tanA)/(1-tanAtanA)=2tanA/[1-tan2A]

降幂公式

cosA^2=[1+cos2A]/2

sinA^2=[1-cos2A]/2

tanA^2=[1-cos2A]/[1+cos2A]

变式：

sin2α=sin^2(α+π/4)-cos^2(α+π/4)=2sin^2(a+π/4)-1=1-2cos^2(α+π/4);　cos2α=2sin(α+π/4)cos(α+π/4)

余弦定理：

a^2=b^2+c^2-2bc*cosA

b^2=c^2+a^2-2ca*cosB

c^2=a^2+b^2-2ab*cosC

三角函数值应用

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三角函数在复数中有较为重要的应用。在物理学中，三角函数也是常用的工具。

它有六种基本函数

符号 sin cos tan cot sec csc

正弦函数sin(A)=a/c

余弦函数cos(A)=b/c

正切函数tan(A)=a/b

余切函数cot(A)=b/a

其中a为对边，b为邻边，c为斜边

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