We have that because the central angle is 90°, the sector represents 1/4 of a circle with a radius of 10 yd.
So, length of the safety rail is given by:
Where:
r = 10 yd
pi = 3.14
Substitute, we have:
The Answer is 15.7 yd
Next, area of the deck is given by:
Substitute the values:
The answer is 78.5 yd^2