Maths Olympiad Prep

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Geometry Difficulty 2.6 Junior Find the answer Canada

JKLMJKLM is a square and PQRSPQRS is a rectangle.Figure 0If JKJK is parallel to PQPQ, JK=8JK=8 and PS=2PS=2, then the total area of the shaded regions is

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Solution

The total area of the shaded regions is the difference between the area of square JKLMJKLM and the area of the portion of rectangle PQRSPQRS that overlaps JKLMJKLM. Since JK=8JK=8, then the area of square JKLMJKLM is 8×88\times8 or 64. Since JKJK is parallel to PQPQ, then the portion of PQRSPQRS that overlaps JKLMJKLM is a rectangle, and has length equal to JKJK or 8, and width equal to PSPS or 2. So the area of the portion of PQRSPQRS that overlaps JKLMJKLM is 8×2=168\times2=16. Therefore the total area of the shaded regions is 6416=4864-16=48.

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Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.