In a Δ ABC, if L and M are points on AB and AC respectively such that LM||BC. Prove that:

(i) ar(Δ LCM) = ar(Δ LBM)


(ii) ar(Δ LBC) = ar(Δ MBC)


(iii) ar(Δ ABM) = ar(Δ ACL)


(iv) ar(Δ LOB) = ar(Δ MOC)

(i) Clearly, triangles LMB and LMC are on the same base LM and between the same parallels LM and BC.

Therefore,


Area ( = Area () (1)


(ii) We observe that triangles LBC and MBC are on the same base BC and between the same parallels LM and BC.


Therefore,


Area (ΔLBC) = Area (ΔMBC) (2)


(iii) We have,


Area ( = Area ( [From (i)]


Area ( + Area ( = Area ( + Area (


Area ( = Area (


(iv) We have,


Area ( = Area ( [From (ii)]


Area (LBC) - Area ( = Area ( - Area (


Area ( = Area ()


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