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In triangle ABCABC, points DD and EE are on ABAB and ACAC respectively such that DEDE is parallel to BCBC. If AD=6AD = 6 cm, DB=4DB = 4 cm, AE=9AE = 9 cm, then the length of ECEC (in cm) is:

Solution

Correct Option: 3

Since DE is parallel to BC, by the Basic Proportionality Theorem (or Thales' theorem), we have:

ADDB=AEEC\frac{AD}{DB} = \frac{AE}{EC}

Substituting the known values:

64=9EC\frac{6}{4} = \frac{9}{EC}

Cross-multiplying gives:

6EC=496 \cdot EC = 4 \cdot 9

6EC=366 \cdot EC = 36

Dividing both sides by 6:

EC=6EC = 6 cm.

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