A square has an area of 40 square feet. What is the length of a side of the square, in feet?

The length of side can be calculated as  

s = √40

  = √4x10

  = 2√10

Step-by-step explanation:

10

Step-by-step explanation: A square has 4 sides and 40 is diviable by 10 so it must be 10.

c.

step-by-step explanation:

she should of added 9^2 and 12^2. that is because it is a^2+b^2=c^2. c^2 is the hypotenuse and should always be bigger than the other two numbers. which is why she should of added 9 squared and 12 squared together instead of 15 squared.