9514 1404 393
Answer:
a) 96 m²
b) 26,000 ft²
Step-by-step explanation:
The area of the unshaded region is the difference between the overall area of the rectangle and the area of the shaded region. It can also be found directly using the dimensions of the unshaded region.
a) We have the height of the right triangle, but need to know its base. The Pythagorean theorem can help with that. Let the base of the triangle be represented by x. Then ...
x² +16² = 20²
x² = 400 -256 = 144
x = √144 = 12
The area of the unshaded triangle is given by the formula ...
A = (1/2)bh
A = (1/2)(12)(16) = 96 . . . . square meters
__
b) The shaded area at upper left is a square 100 ft on a side. Its area is ...
A = s² = (100 ft)² = 10,000 ft²
The shaded area at upper right is a triangle with base and height 120 ft and 150 ft. Its area is ...
A = (1/2)bh = (1/2)(120 ft)(150 ft) = 9,000 ft²
The area of the overall rectangle is ...
A = LW = (300 ft)(150 ft) = 45,000 ft²
So, the unshaded area is ...
unshaded area = overall area - left shaded area - right shaded area
unshaded area = 45,000 ft² -10,000 ft² -9,000 ft² = 26,000 ft²
and 
, 
.