9514 1404 393
Answer:
24 cm²
Explanation:
To find the area of the trapezium, we must know the length CD. That means we must know the length BC. Fortunately, the perimeter of ABCF is given, so we have ...
P = 2(AB +BC)
BC = (P/2) -AB = (20 cm)/2 - 6 cm = 4 cm
Then CD is ...
CD = BD -BC = 9 cm -4 cm = 5 cm
The area of the trapezium is given by the formula ...
A = (1/2)(b1 +b2)h
A = (1/2)(5 cm + 3 cm)(6 cm) = 24 cm²
The area of trapezium CDEF is 24 cm².