I really need help with question 11

Area of a circle is PI x r^2, where r is the radius ( half the diameter).

Set up the equation to solve for r:

40 = PI x r^2

r^2 = 40/PI

r = SQRT(40/PI)

r = sqrt(40/3.14)

r = sqrt(12.74)

r = 3.57

Diameter = 2 x 3.57

Diameter = 7.14 feet.

1. d.90

2. e. none of these (80)

3. a. 0

4. b. 6

5. e. none of these (10)

6. a. 5

step-by-step explanation:

step 1: solve one of the equations for one of the variables. let's solve the first equation for y:

step 2: substitute that equation into the other equation, and solve for x.

step 3: substitute x = 4 x = 4 x=4 into one of the original equations, and solve for y.