Cosine in trigonometry is the adjacent divided hypotenuse, in the form of ${\displaystyle \cos \theta ={\frac {a}{h}}}$ An equation with Cosine would be the following when the adjacent is equal to 5 and the hypotenuse is equal to 10: ${\displaystyle \cos \theta ={\frac {a}{h}}}$ = ${\displaystyle \cos \theta \ ={\frac {5}{10}}=.877562}$

Cosine is usually used for triangle with the angle in the corner of lower point of the hypotenuse.