### Theory:

The Perimeter of a Trapezium: The Perimeter is the sum of all side lengths
Perimeter = $$a+b+c+d$$

Midsegment of Trapezium:
• The Segment, connecting midpoints of lateral sides of trapezium, is called midsegment of Trapezium.
• Midsegment of a trapezium is parallel to bases and is equal to half of their sum.

$\begin{array}{l}\mathit{EF}\parallel \mathit{BC},\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\mathit{EF}\parallel \mathit{AD};\\ \\ \mathit{EF}=\frac{\mathit{BC}+\mathit{AD}}{2}.\end{array}$

Trapezium has only one midsegment.