Difficulty: Medium
Correct Answer: 1 : 2
Explanation:
Introduction:
This question tests how a square’s diagonal relates to its side and how that affects area. The diagonal of a square is longer than its side by a factor of sqrt(2). If a new square is constructed on the diagonal of the original square, that diagonal becomes the side length of the new square. Since area depends on side^2, the ratio of areas becomes a clean constant. The key is to express both areas in terms of the original side length s and simplify.
Given Data / Assumptions:
Concept / Approach:
Diagonal of a square: d = s*sqrt(2). New square side equals d, so new area = d^2 = (s*sqrt(2))^2 = 2s^2. Ratio original:new = s^2 : 2s^2 = 1:2.
Step-by-Step Solution:
Step 1: Assume original side = s.Original area = s^2Step 2: Compute diagonal of original square.Diagonal d = s*sqrt(2)Step 3: New square has side equal to the diagonal.New side = d = s*sqrt(2)Step 4: Compute new square area.New area = (s*sqrt(2))^2 = s^2 * 2 = 2s^2Step 5: Form ratio of areas.Original : New = s^2 : 2s^2 = 1 : 2
Verification / Alternative check:
Let s = 10. Original area = 100. Diagonal = 10*1.414 ≈ 14.14. New square area = (14.14)^2 ≈ 200. Ratio 100:200 = 1:2. The numerical check confirms the algebraic ratio exactly.
Why Other Options Are Wrong:
2:1 would imply the new square has smaller area, which is impossible because its side is the diagonal (longer than s).2:3, 3:1, and 4:1 are inconsistent with the exact factor of 2 produced by squaring sqrt(2).Only 1:2 matches the exact relationship.
Common Pitfalls:
• Forgetting that diagonal = s*sqrt(2) (using s/2 or another incorrect relation).• Comparing side lengths instead of areas (areas require squaring).• Reversing the ratio while writing the final answer.
Final Answer:
The ratio of areas is 1 : 2.
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