Answer:
2.91 units
Explanation:
If and only if this is a right triangle, we can apply the some fimctopm to determine the length of side BD:
side BC
tan 20 degrees = ---------------
8
or side BC = 8 tan 20 degrees. Since tan 20 degrees = 0.364 radians,
side BC has length 8(0.364) = 2.91 units