DepEd MELC reviewer for Grade 7 Mathematics, Quarter 3. Study the rules, worked formulas, and exam hacks below.
1
Angles and Angle Pairs
| Pair | Definition |
|---|---|
| Complementary | Two angles that sum to 90° |
| Supplementary | Two angles that sum to 180° |
| Vertical | Opposite angles formed by intersecting lines — equal |
| Adjacent | Share a side and vertex |
💡 Exam Hack
Complementary = Corner (90°). Supplementary = Straight line (180°).
2
Polygons
A polygon is a closed figure made of line segments. The sum of interior angles depends on the number of sides (n).
Sum of interior angles = (n − 2) × 180°
| Polygon | Sides | Angle sum |
|---|---|---|
| Triangle | 3 | 180° |
| Quadrilateral | 4 | 360° |
| Pentagon | 5 | 540° |
| Hexagon | 6 | 720° |
3
Basic Geometric Terms
Know point, line, ray, segment, and plane. A line extends forever; a segment has two endpoints; a ray has one endpoint.
4
Worked Example
Find the interior angle sum of an octagon (8 sides).
(8 − 2) × 180° = 6 × 180° = 1080°
Each angle of a REGULAR octagon = 1080° ÷ 8 = 135°.
📌 Quick Recap — Master These
Before your test, make sure you can confidently do each of the following:
- Explain and apply Angles and Angle Pairs.
- Explain and apply Polygons.
- Explain and apply Basic Geometric Terms.
- Explain and apply Worked Example.
Re-read any section above where you hesitate, then try the worked example again without looking.