In the given figure, P and Q are the mid-points of AC and AB, respectively. Also, PG = GR and HQ = HR. Calculte the ratio of area of ΔPQR to area of ΔABC.
Construction: Join P and H.
PQ||BC and PQ=12BC [Mid point theorem].
Also, Area (ΔPQH)=14Area(ΔABC)...(I)
Area (quad. PGHQ) =34Area(ΔPQR)−−−(II)
[Since GH||PQ and GH =12PQ]
Also, Area (ΔPGH)=12 Area (ΔPQH)−−−−(III)
[Since they have same height but base (ΔPGH)=Base(ΔPQH)2 or GH=12PQ]
Area (quad. PGHQ)=Area (ΔPQH) +Area (ΔPGH)
From (I),(II) and (III).
34 Area (ΔPQR)=14 Area (ΔABC)+38 Area (ΔPQR)
Simplifying, we get.
Area(ΔPQR)Area(ΔABC)=23