# Cosine Graph

Cosine is one of the most important trigonometric functions. Cosine of an angle is defined in right-angled triangle. Let us consider a right angled triangle ABC as shown in the given figure:

Cosine of angle $\theta$ is given by the following formula:

The values of cosine of few important angles are given below:

cos 0$^o$ | 1 |

cos 30$^o$ |
$\frac{\sqrt{3}}{2}$ |

cos 45$^o$ |
$\frac{1}{\sqrt{2}}$ |

cos 60$^o$ |
$\frac{1}{2}$ |

cos 90$^o$ |
0 |