Congruency Criterion for Triangles AAS, ASA, SSS, SAS
Question 5 ii...
Question
Question 5 (iii) In the following figure, ABC and BDE are two equilateral triangles such that D is the mid-point of BC. If AE intersects BC at F, show that:
(iii) ar(ABC) = 2ar(BEC)
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Solution
(iii)
ar (ΔABE)=ar(ΔBEC) (Common base BE and BE||AC) ar(ΔABF)+ar(ΔBEF)=ar(ΔBEC)
We know that,
ar (ΔBEF)=ar(ΔAFD) ar(ΔABF)+ar(ΔAFD)=ar(ΔBEC) ar(ΔABD)=ar(ΔBEC) 12ar(ΔABC)=ar(ΔBEC) ∴ar(ΔABC)=2ar(ΔBEC)