XY is a line parallel to side BC of a triangle ABC. If BE || CA and FC || AB meet XY at E and F respectively, show that area of ∆ABE = area of ∆ACF.
Answers
Answer:
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area of ∆ABE = area of ∆ACF
Explanation:
Given: XY is a line parallel to side BC of a triangle ABC.
BE || CA and FC || AB meet XY at E and F respectively
To prove: area of ∆ABE = area of ∆ACF.
Proof: Let XY intersect AB and BC at M and N respectively.
As XY || BC, then EN || BC.
Also BE || AC, then BE || CN.
BCNE is a parallelogram as the opposite sides are parallel.
Parallelogram BCNE and ∆AEB lie on the same base BE, and lie between same parallel lines BE and AC.
So area of ∆AEB = 1/2 area of BCNE ----------------------(1)
Similarly, area of ∆ACF = 1/2 area of BCFM ----------------------(2)
Parallellograms BCNE and BCFM are on the same base BC and lie between the same parallel lines BC and EF.
So area of BCNE = area of BCFM ----------------------(3)
From (1), (2) and (30), we get:
area of ∆ABE = area of ∆ACF
Hence proved.