The image shows a classroom blackboard with various geometric concepts written on it. Here's a breakdown of the content:

1. Adjacent Angles:

   • The term "adjacent" is noted with the condition "common side."

2. Complementary and Supplementary Angles:

   • "Complementary ∠25 + ∠65 = 90°"
   • "Supplementary ∠25 + ∠180°"

3. Relationships between angles and lines:
   There is a diagram showing lines, labeled points D, E, and R, with certain angles marked:

   • The notation "∠1 + ∠2 = 90°"
   • "∠1 + ∠2 = 180°" (probably referring to linear pairs or supplementary angles).

4. Polygon properties:

   • The term "regular polygon" appears, next to a figure with equal sides, indicating it might be a regular pentagon.
   • "Convex" is also written next to the polygon, suggesting the concept of convex polygons.

5. Additional angle properties:

   • A mention of "Supplement" or "Supplementary" angles is seen at the bottom of the board.

Would you like me to explain any of these geometric concepts in detail? Here are 5 related questions:

1. How are adjacent angles defined geometrically?
2. What is the difference between complementary and supplementary angles?
3. How can you identify a regular polygon based on side lengths and angles?
4. What are the properties of convex polygons?
5. What is the relationship between linear pairs and supplementary angles?

Tip: When dealing with angle relationships, always remember that complementary angles add up to 90°, while supplementary angles sum to 180°.