In a triangle ABC, E is the mid-point of median AD. Show that ar (BED) =1/4 ar(ABC)
Given: Δ ABC, with AD as median i.e., BD = CD and E is the mid-point of AD, i.e., AE = DE
To prove: ar (BED) = 1/4 ar (ABC).
Proof: AD is a median of Δ ABC and median divides a triangle into two triangles of equal area
∴ ar(ABD) = ar(ACD)
⇒ ar (ABD) = 1/2 ar (ABC) …(1)
In Δ ABD,
BE is median (As E is mid-point of AD)
median divides a triangle into two triangles of equal area
∴ ar(BED) = ar(BEA)
⇒ ar (BED) = 1/2 ar (ABD)
⇒ ar (BED) = 1/2 × 1/2 ar (ABC) (from (1): ar (ABD) = 1/2 ar (ABC))
⇒ ar (BED) = 1/4 ar (ABC)
Hence proved.