Geometry & Measurement
Area, perimeter, angles, and coordinate geometry
Explanation
Perimeter & Area Formulas
| Shape | Perimeter | Area |
|---|---|---|
| Rectangle | 2(l + w) | l × w |
| Square | 4s | s² |
| Triangle | a + b + c | ½ × base × height |
| Circle | 2πr (circumference) | πr² |
Remember: perimeter is in units; area is in square units.
Angles
- Right angle: exactly 90°
- Straight angle: exactly 180°
- Angles in a triangle: always sum to 180°
- Vertical angles (opposite when two lines cross): equal
- Supplementary: two angles that add to 180°
- Complementary: two angles that add to 90°
Coordinate Plane
Points are written as (x, y) — x goes left/right, y goes up/down.
- Quadrant I: (+, +) II: (−, +) III: (−, −) IV: (+, −)
- Distance formula (horizontal/vertical lines): |x₁ − x₂| or |y₁ − y₂|
- To find the midpoint: average the x-coordinates and average the y-coordinates.
Practice Questions
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What does Geometry & Measurement cover in the ISEE Lower Level exam?
Area, perimeter, angles, and coordinate geometry.
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