Firstly , we need to locate some unknowns
we can find angle t
Let's take bigger triangle first
[tex] sin(t)=\frac{12}{30} [/tex]
now, we can take smaller triangle to find h
[tex] sin(t)=\frac{h}{20} [/tex]
now, we can plug value of sin(t) here
and we get
[tex] \frac{12}{30}=\frac{h}{20} [/tex]
now, we can find h
[tex] h=20*\frac{12}{30} [/tex]
[tex] h=8ft [/tex]..............Answer