To determine the measure of angle 3, given that lines 1 and 2 are parallel, we need more details about the specific angles involved. Typically, when dealing with parallel lines and a transversal, the following angle relationships apply:

1. Corresponding Angles – Angles in the same relative position are equal.
2. Alternate Interior Angles – Angles on opposite sides of the transversal but inside the parallel lines are equal.
3. Alternate Exterior Angles – Angles on opposite sides of the transversal but outside the parallel lines are equal.
4. Consecutive Interior Angles – Interior angles on the same side of the transversal sum to 180 degrees.

If you provide more details, such as a diagram or angle values, I can determine the exact measure of angle 3.

Would you like to upload an image for clarification?

Here are five related questions to expand your understanding:

1. What are the properties of corresponding angles in parallel lines?
2. How do alternate interior angles help in solving geometric problems?
3. What is the sum of consecutive interior angles in parallel lines?
4. How can exterior angles be used to find missing angles?
5. What are the applications of parallel line theorems in real life?

Tip: When working with parallel lines and transversals, always look for given angle measures and their relationships to quickly find unknown angles.