CBSE Guess > Papers > Question Papers > Class X > 2009 > Mathematics > Mathematics
Q. 28 . Prove that the ratio of the areas of two similar triangles is equal to the square of the ratio of their corresponding sides. Using the above, do the following .
If D is a point on the side AC of 
such that
AD : DC = 2 : 3, and E is a point on BC such that
DE || AB; then find the ratio of areas of 
and 
.
Sol. Part I: See Theorem 2,
Page (xxxi).
Part II:
Let AD = 2k, CD = 3k
Then AC = 2k + 3k = 5k
Q. 29. A farmer connects a pipe of internal diameter 25 cm from a canal into a cylindrical tank in his field, which is 12 m in diameter and 2.5 m deep. If water flows through the pipe at the rate of 3.6 km/h, in how much time will the tank be filled? Also find the cost of water, if the canal department charges at the rate of Rs. 0.07/m3. 
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