Difficulty: Easy
Correct Answer: (-0.5, -6)
Explanation:
Introduction / Context:
Reflections in coordinate geometry are a basic but important concept, often used to describe symmetry. Reflecting a point across the x-axis changes only the vertical position of the point, while its horizontal position remains the same. This question tests whether you understand how the y coordinate changes while the x coordinate is preserved during a reflection in the x-axis.
Given Data / Assumptions:
Concept / Approach:
When a point (x, y) is reflected across the x-axis, its x coordinate remains unchanged and its y coordinate changes its sign. In other words, a point (x, y) becomes (x, -y). This rule follows from the property that the x-axis is the set of points with y = 0, and reflection across it reverses the vertical distance above or below this axis.
Step-by-Step Solution:
Step 1: Start with the original point P having coordinates (-0.5, 6).
Step 2: Identify the x coordinate x = -0.5 and the y coordinate y = 6.
Step 3: Reflect across the x-axis by keeping x the same and changing y to -y.
Step 4: Compute the new y coordinate: -y = -6.
Step 5: The reflected point P' therefore has coordinates (-0.5, -6).
Step 6: This point lies directly below the original point at the same horizontal position.
Verification / Alternative check:
The distance from the original point to the x-axis is 6 units (since its y coordinate is 6). After reflection, the new point should be 6 units below the x-axis, so its y coordinate should be -6. The midpoint of the segment joining (-0.5, 6) and (-0.5, -6) is (-0.5, 0), which lies on the x-axis. This confirms that the reflection has been done correctly.
Why Other Options Are Wrong:
Common Pitfalls:
Students sometimes confuse reflections across the x-axis and y-axis, or mistakenly change both coordinates. Always remember: reflection in the x-axis changes only the sign of the y coordinate. Reflection in the y-axis changes only the sign of the x coordinate. Keeping this distinction clear helps avoid confusion in coordinate geometry questions.
Final Answer:
Therefore, the reflection of the point (-0.5, 6) in the x-axis is (-0.5, -6).
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