Measure each of the angles.

To accurately measure these angles, you will need a protractor. Since I cannot physically use a protractor on the image, I will explain how you can measure each angle yourself.

Instructions for measuring angles:

1. Place the center point of your protractor exactly on the vertex (the corner) of the angle.
2. Align the baseline (the $0^\circ$ line) of the protractor with one of the arms of the angle.
3. Read the measurement where the other arm of the angle crosses the protractor's scale. Use the correct scale (inner or outer) depending on which side the angle opens from your baseline.

Let's look at each angle:

• a. This is an acute angle (less than $90^\circ$).

  • Place the protractor's center on the vertex. Align the $0^\circ$ line with the bottom arm. Read the value where the top arm crosses the scale.
  • Based on visual estimation, this angle appears to be approximately $\boxed{15^\circ \text{ to } 20^\circ}$.

• b. This is an acute angle (less than $90^\circ$).

  • Place the protractor's center on the vertex. Align the $0^\circ$ line with the bottom arm. Read the value where the top arm crosses the scale.
  • Based on visual estimation, this angle appears to be approximately $\boxed{30^\circ \text{ to } 35^\circ}$.

• c. This is an obtuse angle (greater than $90^\circ$ but less than $180^\circ$).

  • Place the protractor's center on the vertex. Align the $0^\circ$ line with the bottom arm. Read the value where the top arm crosses the scale. Remember to use the scale that starts from $0^\circ$ on the aligned arm and goes up past $90^\circ$.
  • Based on visual estimation, this angle appears to be approximately $\boxed{120^\circ \text{ to } 130^\circ}$.

Please use a physical protractor to get the exact measurements.