DE is the long narrow side, so judging from the picture, we can assume that DE is 6.
If the width is 8ft and the length is twice the width then multiply 8 by 2 to find your length
Answer:

Step-by-step explanation:
you have that the average sped is given by the following formula:

The uncertainty formula for a division is given by:
(1)
Δv: uncertainty in speed
Δx: uncertainty in the distance = 0.9m
Δt: uncertainty in time = 0.7s
x: distance = 8.1m
t: time = 1.7s
You replace the values of all parameters in the equation (1):

Hence, the relation between the uncertainty in the average velocity is 0.426