Answer:
To answer this question, you need to find the area of the trapezoid that forms the poster. A trapezoid is a quadrilateral with one pair of parallel sides. The area of a trapezoid is given by the formula:
Area = (1/2) * (base1 + base2) * height
where base1 and base2 are the lengths of the parallel sides and height is the perpendicular distance between them.
In this case, the parallel sides are a and c, and the height is d. So, plugging in the given values, we get:
Area = (1/2) * (11 + 15) * 20
Area = (1/2) * 26 * 20
Area = 13 * 20
Area = 260 cm^2
Therefore, the area of the poster is 260 cm^2.
Explanation: