Measuring Angles Using a Protractor

We will read the measurement from the __________ scale.

Is this the correct way of using a protractor to measure angles?

∠DEF = ______°

Is this the correct way of using a protractor to measure an angle?

Is this an 85° angle?

Why is this not a 85° angle?

This is the wrong way of using a protractor because:

• the bottom line of the angle is not aligned to the baseline of the protractor.
• the vertex of the angle is not aligned to the centre of the protractor.

Do you agree that ∠a = 90°?

We should read the measurement based on the inner scale because '0' starts from the ______.

∠a = ______°