the area of the green square is 9 ft2. the area of the yellow square is 25 ft2.
what is the area of the red square (labelled "b" in the diagram)?

area = 16 ft²

Step-by-step explanation:

The area of the green square = 9 ft²

area of the yellow square = 25 ft²

Area of the red square can be computed as follows:

area of a square = L²

Since one side of each triangle forms a part of the triangle knowing the length of sides of the green and yellow triangle can be use to get the sides of the red square and invariably the area.

Green square

L² = 9

square both sides

√L² = √9

L = 3 ft

Yellow square

L² = 25

square both sides

√L² = √25

L = 5 ft

use Pythagoras theorem to get the third side of the triangle which is the b

c² = a² + b²

b² = c²  - a²

a = 3 ft

c = 5 ft

b² =  5² - 3²

b² = 25 - 9

b² = 16

square both sides

√b² = √16

b = 4

Red square

area = L²

area = 4²

area = 16 ft²