The cross-sectional area of a trench that is 5 feet wide and 3 feet deep is:

The cross-sectional area of a trench that is 5 feet wide and 3 feet deep is:

• A. 12 square feet
• B. 15 square feet
• C. 18 square feet
• D. 21 square feet

Answer: (B)

Cross-sectional area for a rectangular trench is found by multiplying its width by its depth. With a width of 5 feet and a depth of 3 feet, the area is 5 × 3 = 15 square feet. This follows the basic area rule for rectangles, which applies to trench cross-sections shaped like a rectangle. The other numbers would result from different dimension pairs (for example, 4 by 3 gives 12, 6 by 3 gives 18, 7 by 3 gives 21), but with these dimensions the correct area is 15 square feet.

Cross-sectional area for a rectangular trench is found by multiplying its width by its depth. With a width of 5 feet and a depth of 3 feet, the area is 5 × 3 = 15 square feet. This follows the basic area rule for rectangles, which applies to trench cross-sections shaped like a rectangle. The other numbers would result from different dimension pairs (for example, 4 by 3 gives 12, 6 by 3 gives 18, 7 by 3 gives 21), but with these dimensions the correct area is 15 square feet.