Trigonometry
[tex]Sin\frac{Opposite}{Hypotenuse} Cos\frac{Adjacent}{Hypotenuse} Tan\frac{Adjacent}{Opposite}[/tex]
[tex]S\frac{O}{H} C\frac{A}{H} T\frac{A}{O}[/tex]
You know the hypotenuse and you want to find the opposite therefore you use, sine.
[tex]Opposite = Sin(70) *{20}[/tex]
Opposite = 18.79385242
Opposite = 18.8 feet
