A student uses a protractor to draw angle PQR = 142°. She starts with ray QP pointing to the right. She accidentally reads the inner scale throughout. Which angle does she actually draw?
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Worked Solution
Step 1: On a standard protractor, the inner and outer scales are supplementary — they sum to 180° at any mark.
Step 2: At the mark the student reads as 142° (outer scale), the inner scale shows 180° − 142° = 38°.
Step 3: She draws a 38° angle instead of 142°.
Check: 38° + 142° = 180°. ✓
Correct answer: 38°
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