Which of the following is the correct area formula for a trapezoid with bases b1 and b2 and height h?

• A. A = b1 b2 h
• B. A = 1/2 (b1 + b2) h
• C. A = 1/2 (b1 - b2) h
• D. A = (b1 + b2) h

Answer: (B)

Area of a trapezoid comes from averaging the two base lengths and multiplying by the height. The correct form is A = [(b1 + b2) / 2] × h. This fits intuition: if you could reshape the trapezoid into a rectangle without changing area, its width would effectively be the average of the two bases, and multiplying by the height gives the area.

A quick check: if the two bases are equal (a rectangle), the formula reduces to A = (b1 + b1)/2 × h = b1 × h, which matches the familiar rectangle area.

Why the other forms don’t fit: multiplying the two bases by height would give a volume-like unit (length^3), not area. using the difference of bases would not correspond to any standard area derivation. and using the sum of bases without the 1/2 factor gives double the correct area.