Question

3. In the figure below, E is on AD and C is on BD. The dimensions given are in meters. What is the length, in meters, of CD?

A. 2,640
B. 2,784
C. 3,960
D. 4,400
E. 5,840

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Answer 1

C. 3,960

Explanation:

∆ADB ~ ∆EDC. Therefore,

`(AB)/(EC) = (DB)/(DC)`

`(2,000)/(1,200) = (2,640 + x)/(x)` (substitution)

Solve for x

`(5)/(3) = (2,640 + x)/(x)`

Cross multiply

`5*x = 3(2,640 + x)`

`5x = 7,920 + 3x`

5x - 3x = 7,920

2x = 7,920

x = 7,920/2

x = 3,960 meters