Question

In ∆ABC, AB = 5 cm, BC = 8 cm and CA = 7 cm. If D and E are respectively the mid-points of AB and BC, then DE = __________.

Answer 1

Given:
In ∆ABC, AB = 5 cm, BC = 8 cm and CA = 7 cm
D and E are respectively the mid-points of AB and BC


Using mid-point theorem: The line segment joining the mid-points of two sides of a triangle is parallel to the third side and is equal to the half of it.

Therefore,
$$\begin{gathered} DE=\frac{1}{2}\left(AC\right) \\ =\frac{1}{2}\times 7 \\ =3.5\mathrm{cm} \end{gathered}$$


Hence, DE = 3.5 cm.