Question

In a $\Delta ABC,D,E$ and F are respectively, the mid-points of BC, CA and AB. If the lengths of side AB, BC and CA are 7cm, 8cm and 9 cm, respectively, find the perimeter of $\Delta DEF$.

Answer 1

In $\Delta ABC,D,EandF$ are the mid -points of sides, BC, CA , AB respectively

AB = 7cm, BC = 8cm and CA = 9cm

$\because$ D and E are the mid points of BC and CA

$\therefore$ DE || AB and DE = $\frac{1}{2}AB=\frac{1}{2}\times 7=3.5cm$

Similarly,

$EF=\frac{1}{2}BC=\frac{1}{2}\times 8=4cm$

and $FD=\frac{1}{2}AC=\frac{1}{2}\times 9=4.5cm$

$\therefore$ Perimeter of $\Delta DEF$,

=3.5 + 4+4.5 = 12 cm