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The midpoints of sides ABAB, BCBC, and ACAC in △ABC\triangle ABC are MM, NN, and PP, respectively. The medians drawn from AA, BB, and CC intersect the line segments MPMP, MNMN and NPNP at XX, YY, and ZZ, respectively. If the area of △ABC\triangle ABC is 14401440 sq cm, then the area, in sq cm, of △XYZ\triangle XYZ is

Entered answer:

Solution

✅ Correct Answer: 90

We have triangle ABC with area = 1440 sq cm. M, N, P are midpoints of sides AB, BC, AC respectively.

Solution figure for CAT 2024 QA question 11 (Geometry)

The medians of triangle ABC intersect triangle MNP at points X, Y, Z.

Solution figure for CAT 2024 QA question 11 (Geometry)

The trickest part of this question is getting the graph right. Post which, the solution is pretty simple.


When you connect the midpoints of a triangle's sides, you get the medial triangle.

The medial triangle has area = 14\tfrac{1}{4} × (original triangle's area)

The medial triangle is similar to the original triangle with scale factor 12\tfrac{1}{2}. Since area scales as (scale factor)2^2, we get (12)2=14\left(\tfrac{1}{2}\right)^2 = \tfrac{1}{4}.

Area of triangle MNP = 14×1440=360\tfrac{1}{4} \times 1440 = 360 sq cm


When the medians of a triangle intersect the sides of its medial triangle, the resulting triangle has area equal to 116\tfrac{1}{16} of the original triangle's area. XYZ is nothing but the triangle from the median of MNP (hence, 14\tfrac{1}{4} of MNP). It's like a shrunk up triangle of ABC.

This is a specific case that comes from the properties of medians and how they interact with medial triangles.


Area of triangle XYZ = 116×\tfrac{1}{16} \times Area of triangle ABC

Area of triangle XYZ = 116×1440=90\tfrac{1}{16} \times 1440 = 90 sq cm


Therefore, the area of triangle XYZ is 90 sq cm.

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