Trigonometric Formulas

Formulas /திரிகோணகணித சமன்பாடுகள்  



♣ $sin^{ 2 }\alpha \quad +\quad cos^{ 2 }\alpha \quad =\quad 1$

♣ $1\quad +\quad tan^{ 2 }\alpha \quad =\quad sec^{ 2 }\alpha \\ $

♣ $1\quad +\quad cot^{ 2 }\alpha \quad =\quad cosec^{ 2 }\alpha \\ $

☀$tan\alpha =\frac { sin\alpha  }{ cos\alpha  } $

☀$cot\alpha =\frac { cos\alpha  }{ sin\alpha  } $


Addition and Subtraction Formulas

♣ $sin(\alpha +\beta )\quad =\quad sin\alpha .cos\beta \quad +\quad sin\beta .cos\alpha $

♣ $sin(\alpha -\beta )\quad =\quad sin\alpha .cos\beta \quad -\quad sin\beta .cos\alpha $

♣ $cos(\alpha +\beta )\quad =\quad cos\alpha .cos\beta \quad -\quad sin\beta .sin\alpha $

♣ $cos(\alpha -\beta )\quad =\quad cos\alpha .cos\beta \quad +\quad sin\beta .sin\alpha $

♣ $tan(\alpha +\beta )\quad =\quad \frac { tan\alpha \quad +\quad tan\quad \beta  }{ 1-tan\alpha .tan\beta  } $

♣ $tan(\alpha -\beta )\quad =\quad \frac { tan\alpha \quad -\quad tan\quad \beta  }{ 1+tan\alpha .tan\beta  } $

Double Angle Formulas

♣ $sin2\alpha =sin\alpha .cos\alpha $

♣ $cos2\alpha \quad =\quad cos^{ 2 }\alpha \quad +\quad sin^{ 2 }\alpha \quad =\quad 1\quad -\quad 2sin^{ 2 }\alpha \quad =\quad 2cos^{ 2 }\alpha \quad -\quad 1$

 ♣ $tan2\alpha \quad =\quad \frac { 2tan\alpha  }{ 1-tan^{ 2 }\alpha  } \quad =\quad \frac { 2 }{ cot\alpha \quad -\quad sin\alpha  } $

Triple angle Formulas

♣ $sin3\alpha =3sin\alpha -4sin^{ 3 }\alpha $

♣ $cos3\alpha =4cos^{ 3 }\alpha \quad -\quad 3cos\alpha \\ \\ $

♣ $tan3\alpha \quad =\frac { 3tan\alpha -tan^{ 3 }\alpha  }{ 1-3tan^{ 2 }\alpha  } \\ \\ $


Half Angle Tangent Identities

♣ $sin\alpha \quad =\quad \frac { 2tan\frac { \alpha  }{ 2 }  }{ 1+tan^{ 2 }\frac { \alpha  }{ 2 }  } $

♣ $cos\alpha \quad =\quad \frac { 1-tan^{ 2 }\frac { \alpha  }{ 2 }  }{ 1+tan^{ 2 }\frac { \alpha  }{ 2 }  } $

♣ $tan\alpha \quad =\quad \frac { 2tan\frac { \alpha  }{ 2 }  }{ 1-tan^{ 2 }\frac { \alpha  }{ 2 }  } $


Transforming of Trigonometric Expressions to Product

♣ $sin\alpha \quad +\quad \quad sin\beta  \quad =2sin\frac { \alpha +\beta  }{ 2 } cos\frac { \alpha -\beta  }{ 2 } $

♣ $sin\alpha \quad -\quad \quad sin\beta  \quad =2cos\frac { \alpha +\beta  }{ 2 } sin\frac { \alpha -\beta  }{ 2 } $

♣ $cos\alpha \quad +\quad \quad cos\beta \quad =2sin\frac { \alpha +\beta  }{ 2 } cos\frac { \alpha -\beta  }{ 2 } $

♣ $cos\alpha \quad +\quad \quad cos\beta \quad =-2sin\frac { \alpha +\beta  }{ 2 } sin\frac { \alpha -\beta  }{ 2 } =2sin\frac { \alpha +\beta  }{ 2 } sin\frac { \beta -\alpha  }{ 2 } $

Trigonometric Formulas

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