The problem states that the length of the middle base of a trapezium is 15 cm and the height is 8 cm. We need to find the area of the trapezium.

GeometryTrapeziumAreaGeometric Formulas
2025/4/27

1. Problem Description

The problem states that the length of the middle base of a trapezium is 15 cm and the height is 8 cm. We need to find the area of the trapezium.

2. Solution Steps

The area of a trapezium is given by the formula:
Area=12(a+b)hArea = \frac{1}{2} (a + b) h
where aa and bb are the lengths of the parallel sides (bases) and hh is the height.
The "middle base" of a trapezium is the line segment connecting the midpoints of the non-parallel sides. Its length is equal to the average of the lengths of the two parallel sides. Let the length of the middle base be mm. Then,
m=a+b2m = \frac{a + b}{2}
We are given that m=15m = 15 cm and h=8h = 8 cm. We can rewrite the area formula as:
Area=(a+b2)h=mhArea = (\frac{a + b}{2}) h = m h
Plugging in the given values:
Area=15×8Area = 15 \times 8
Area=120Area = 120

3. Final Answer

The area of the trapezium is 120 cm2^2. Therefore, the answer is B.
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