The area of a trapezium is represented as follow
1/2 * (a + b) * h
According to your diagram
a = 4 mm
b = 10 mm
h = 10 mm (note this is the side opposite the side with 11 mm)
Inputing the value in the formular we have
area = 1/2 * (4 + 10) * 10
area = 1/2 * (14) * 10
area = 1/2 * 140
area = 140/2
area = 70 mm squared.