Final answer:
To determine the amount of fencing required, Mr. Cruz should calculate the circumference of his circular garden, using the formula C = 2πr, where π is approximately 3.14159 and r is the radius.
Step-by-step explanation:
To determine how much fencing Mr. Cruz needs for his circular garden, he should calculate the circumference of the circle. The circumference is the complete distance around the circle, which is exactly what he needs to know to purchase the correct length of fencing material. The formula for the circumference (C) of a circle is C = 2πr (where π is Pi, approximately 3.14159, and r is the radius of the circle). Therefore, for Mr. Cruz's garden with a radius (r) of 40 meters, the circumference would be C = 2π(40m), which he would use to buy the appropriate amount of fencing.
In contrast, the formula for the area of a circle, which is πr², gives the amount of space contained within the circle. This calculation is not necessary for fencing purposes as it gives the square meters inside the circle, not the linear meters around it.