CAT 1996QA Question 15

Geometric CentersEasy

In ΔABC, ∠B is a right angle, AC = 6 cm, and D is the mid-point of AC. The length of BD is

Answer & solution

Correct answer: 3 cm

  • A

    4 cm

  • B

    6

  • 3 cm

  • D

    3.5 cm

Solution

In a right-angled triangle, the length median to the hypotenuse is half the length of the hypotenuse. Hence, BD = 12 AC = 3 cm. This relationship can be verified by knowing that the diameter of a circle subtends a right
angle at the circumference e.g. in the above figure D is the centre of the circle with AC as diameter. Hence,
∠ABC should be 90°. So BD should be the median to the hypotenuse. Thus, we can see that BD = AD = CD = Radius of this circle.
Hence, BD = 12 diameter = 12 AC = 12 × hypotenuse.

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CAT 1996 QA Q15: In ΔABC, ∠B is a right angle, AC = 6 cm, and D is the mid-point of AC. The length of BD is — Solution | TheCATExam