Answer :
The formula to calculate the area of a triangle
[tex]A=\frac{1}{2}(b\times h)[/tex]where b is the base and h is the height
in this case
A=18
b=6
h=?
we substitute the values
[tex]18=\frac{1}{2}(6)(h)[/tex]we isolate the h
[tex]h=\frac{18\cdot2}{6}=\frac{36}{6}=6[/tex]The height is 6