In the figures below, AB is parallel to CD. Find the unknown angles, a and b.

Here are the solutions for the unknown angles in each figure, assuming AB // CD.

Figure 1:

• Finding $a^\circ$: Since AB // CD, the angle $48^\circ$ and $a^\circ$ are alternate interior angles. Therefore, they are equal.

  $$a^\circ = 48^\circ$$ $$\boxed{a = 48}$$

• Finding $b^\circ$: Since AB // CD, the angle $61^\circ$ and $b^\circ$ are alternate interior angles. Therefore, they are equal.

  $$b^\circ = 61^\circ$$ $$\boxed{b = 61}$$