| --- |
| source: ncert |
| topic: geometry |
| class_level: class_7 |
| chapter: ch14 |
| difficulty: beginner |
| --- |
| |
| Class 7 | Ch14: Symmetry |
| Line symmetry: one half is mirror image. Regular n-sided polygon: n lines of symmetry. |
| Lines of symmetry: Equilateral triangle=3, Square=4, Rectangle=2(midpoints only), Rhombus=2(diagonals), Isosceles=1, Scalene=0, Kite=1, Parallelogram=0, Pentagon=5, Hexagon=6, Circle=infinite. |
| Rotational symmetry: looks same after rotation<360°. Order=number of times in full rotation. Angle=360°÷order. |
| Rotational: Square(order 4, angle 90°), Rectangle(order 2, 180°), Equilateral triangle(order 3, 120°), Hexagon(order 6, 60°), Parallelogram(order 2, 180°), Scalene(order 1=none). |
| Square has BOTH line and rotational symmetry. |
| Parallelogram: NO line symmetry but HAS rotational (order 2). |
| Rectangle: 2 lines symmetry, order 2 rotation. |
| Pentagon: order 5, angle 72°. |
