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In the given figure, l // m // n and D is mid-point of CE. If AE = 12.6 cm, then BD is :

In the given figure, l // m // n and D is mid-point of CE. If AE = 12.6 cm, then BD is : Mid-point Theorem, Concise Mathematics Solutions ICSE Class 9.
  1. 12.6 cm

  2. 25.2 cm

  3. 6.3 cm

  4. 18.9 cm

Mid-point Theorem

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Answer

By mid-point theorem,

The line segment joining the mid-points of any two sides of a triangle is parallel to the third side and is equal to half of it.

By converse of mid-point theorem,

The straight line drawn through the mid-point of one side of a triangle parallel to another, bisects the third side.

In △ AEC,

Given,

⇒ m // n

∴ BD // AE.

D is mid-point of CE.

∴ B is the mid-point of AC. (By converse of mid-point theorem)

Also,

⇒ BD = 12AE=12×12.6\dfrac{1}{2}AE = \dfrac{1}{2} \times 12.6 = 6.3 cm

Hence, Option 3 is the correct option.

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