ABC is a triangle right angled at C. A line through the mid-point M of hypotenuse AB and parallel to BC intersects AC at D. Show that:
(i) D is the mid-point of AC (ii) MD ⊥ AC (iii)
Proof: ∵ EF || DG | by construction
and AE = ED
| ∵ E is the mid-point of AD
∴ AF = FG ...(1)
| A line drawn through the mid-point of a side of a triangle parallel to another side bisects the third side
Again,
DG || EF | by construction
and CD = DB
| ∵ D is the mid-point of
∴ BC FG = GC ...(2)
| A line drawn through the mid-point of a side of a triangle parallel to another side bisects the third side
From (1) and (2),
AF = FG = GC
Now, AF + FG + GC = AC
⇒ AF + AF + AF = AC
| From (1) and (2)
⇒ 3 AF = AC
D, E, F are respectively the midpoints of the sides BC, CA and AB of a triangle ABC. Show that:
(i) BDEF is a parallelogram
(ii) DFEC is a parallelogram.