The formula for the area of a rectangle, which is the shape of a door is:
A=l*w Where l is the length and w is the width of the shape.
The length of the door is 84 inches
l=84 in
The width of the door is 54 inches
w= 54 in
now lets plug in the information into the formula
A=l*w
A=84*54
A=4536 in²
Answer= 4536 in²