The adjacent sides of a parallelogram are $10 m$ and $8 m$. If the distance between the longer sides is $4 m$, find the distance between the shorter sides.

The base and corresponding altitude of a parallelogram are $10 \mathrm{cm}$and $12 \mathrm{cm}$ respectively. If the other altitude is$8 \mathrm{cm}$, and the length of the other pair of parallel sides is $l \mathrm{cm}$ each, then find the value of $l$.

Find the area in square centimetres of a triangle whose base and altitude are as under:

base$=18 \mathrm{cm}$, altitude$=3.5 \mathrm{cm}$