Geometry

Question Analysis

This question is about measuring an angle using a protractor without a clear 0 - degree starting point. The main focus is on accurately reading the scale of the protractor and calculating the angle measurement.

 

Key Concept Explanation

A protractor has two scales (inner and outer). When both sides of the angle intersect the protractor away from 0°, we measure the angle by finding the difference between the scale values on the same scale at the intersection points of the two sides with the protractor.

 

Step - by - Step Solution

1. Determine the scale:

Notice that the initial side of the angle is closer to the left - hand side  of the protractor, so we should use the outer - ring scale.

The outer - ring scale reading of the initial side is .

The outer - ring scale reading of the terminal side is .

 

2. Calculate the angle:

As the outer - ring scale increases counter - clockwise, the measurement of the angle is

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