In a trapezium $\text{ABCD}$,$\overline{\text{AB}}\text{\hspace{0.17em}//\hspace{0.17em}}\overline{\text{CD}}$. $\text{E}$ and $\text{F}$ are the mid-points of $\overline{\text{AD}}$ and $\overline{\text{BC}}$ respectively. If $\text{AB=6cm, CD=8cm}$, then $\text{EF=}$

We know that length of line segment joining mid points of non – parallel sides is equal to half of the sum of the parallel sides.

$\text{EF}=\frac{1}{2}\left(\text{AB+CD}\right)$

$=\frac{1}{2}(6+8)$

$=\frac{1}{2}\left(14\right)$

$=7\text{cm}$