1. **Stating the problem:** We are given a horizontal line with points A, C, and B, and a line from point C forming a 60° angle with the horizontal. We need to find the measure of angle $\angle ACD$. 2. **Understanding the angle:** Since the line from C forms a 60° angle with the horizontal line, and $\angle ACD$ is the angle between the line segment CA (which lies on the horizontal) and the line from C going upward, the measure of $\angle ACD$ is exactly 60°. 3. **Conclusion:** Therefore, $$\angle ACD = 60^\circ$$