Question

use the protractor to measure the angle. ∠ def = \square °

Explanation:

Step1: Align Protractor and Angle

Place the protractor's center on vertex \( E \), align one side (e.g., \( EF \)) with the protractor's \( 0^\circ \) mark.

Step2: Read the Angle

The other side (\( ED \)) aligns with the \( 40^\circ \) mark on the protractor (checking the correct scale, here the inner or outer scale matches the angle's opening).

Answer:

\( 40 \)