高三网 > 高考 > 高考备考 > 高中三角函数所有公式

高中三角函数所有公式

高老师 分享 时间:

  两角和公式

  sin(A+B) = sinAcosB+cosAsinB

  sin(A-B) = sinAcosB-cosAsinB

  cos(A+B) = cosAcosB-sinAsinB

  cos(A-B) = cosAcosB+sinAsinB

  tan(A+B) = (tanA+tanB)/(1-tanAtanB)

  tan(A-B) = (tanA-tanB)/(1+tanAtanB)

  cot(A+B) = (cotAcotB-1)/(cotB+cotA)

  cot(A-B) = (cotAcotB+1)/(cotB-cotA)

  倍角公式

  tan2A = 2tanA/(1-tan^2 A)

  Sin2A=2SinA?CosA

  Cos2A = Cos^2 A--Sin^2 A

  =2Cos^2 A—1

  =1—2sin^2 A

  三倍角公式

  sin3A = 3sinA-4(sinA)^3;

  cos3A = 4(cosA)^3 -3cosA

  tan3a = tan a ? tan(π/3+a)? tan(π/3-a)

  半角公式

  sin(A/2) = √{(1--cosA)/2}

  cos(A/2) = √{(1+cosA)/2}

  tan(A/2) = √{(1--cosA)/(1+cosA)}

  cot(A/2) = √{(1+cosA)/(1-cosA)} ?

  tan(A/2) = (1--cosA)/sinA=sinA/(1+cosA)

  和差化积

  sin(a)+sin(b) = 2sin[(a+b)/2]cos[(a-b)/2]

  sin(a)-sin(b) = 2cos[(a+b)/2]sin[(a-b)/2]

  cos(a)+cos(b) = 2cos[(a+b)/2]cos[(a-b)/2]

  cos(a)-cos(b) = -2sin[(a+b)/2]sin[(a-b)/2]

  tanA+tanB=sin(A+B)/cosAcosB

  积化和差

  sin(a)sin(b) = -1/2*[cos(a+b)-cos(a-b)]

  cos(a)cos(b) = 1/2*[cos(a+b)+cos(a-b)]

  sin(a)cos(b) = 1/2*[sin(a+b)+sin(a-b)]

  cos(a)sin(b) = 1/2*[sin(a+b)-sin(a-b)]

  诱导公式

  sin(-a) = -sin(a)

  cos(-a) = cos(a)

  sin(π/2-a) = cos(a)

  cos(π/2-a) = sin(a)

  sin(π/2+a) = cos(a)

  cos(π/2+a) = -sin(a)

  sin(π-a) = sin(a)

  cos(π-a) = -cos(a)

  sin(π+a) = -sin(a)

  cos(π+a) = -cos(a)

  tgA=tanA = sinA/cosA

  万能公式

  sin(a) = [2tan(a/2)] / {1+[tan(a/2)]^2}

  cos(a) = {1-[tan(a/2)]^2} / {1+[tan(a/2)]^2}

  tan(a) = [2tan(a/2)]/{1-[tan(a/2)]^2}

  其它公式

  a?sin(a)+b?cos(a) = [√(a^2+b^2)]*sin(a+c) [其中,tan(c)=b/a]

  a?sin(a)-b?cos(a) = [√(a^2+b^2)]*cos(a-c) [其中,tan(c)=a/b]

  1+sin(a) = [sin(a/2)+cos(a/2)]^2;

  1-sin(a) = [sin(a/2)-cos(a/2)]^2;;

  其他非重点三角函数

  csc(a) = 1/sin(a)

  sec(a) = 1/cos(a)