Two sides of the triangle that form a 90 degree angle are called the

The two sides of the triangle that are by the right angle are called the legs

Step-by-step explanation:

Step-by-step explanation:

The two sides of the triangle that are by the right angle are called the legs... and the side opposite of the right angle is called the hypotenuse

Given:
Height = 4 feet
Base = 6 feet
so, 
Area of triangle = 1/2 x b x h 
                         = 1/2 x 6 x 4 
                         = 12 feet squared 
 
Area of rectangle = length x width 
                             = a x 6 
                             = 6 a
 
Total area = 6a + 12 
The maximum area = 150 ft^2 
Using inequality
6a +12 must be less than or equal to 150 
6a less than or equal to 150-12 
6a less than or equal to 138 
a less than or equal to 138/6 
a less than or equal to 23 
Hence,
The length of the rectangle should be less than or equal to 23 feet.