Rectilinear Figures

All sides are equal, Diagonals bisect each other at right angles, Opposite angles are equal

Step 1: A rhombus has all sides equal (definition). Step 2: Its diagonals bisect each other at 90° (property). Step 3: Opposite angles are equal (parallelogram property). Step 4: All angles are NOT 90° (that's a square), and diagonals are NOT equal (that's a rectangle).

20 cm

Step 1: The diagonals of a rhombus divide it into 4 congruent triangles. Step 2: If the triangle has sides 5 cm each, then each side of the rhombus is 5 cm. Step 3: Perimeter = 4 × side length = 4 × 5 = 20 cm.

10

Step 1: Use formula (2n - 4) × 90° = 1440°. Step 2: (2n - 4) = 1440°/90° = 16. Step 3: 2n - 4 = 16, so 2n = 20, therefore n = 10 sides.

10 cm

Step 1: In a rectangle, diagonal forms a right triangle with length and breadth. Step 2: Using Pythagoras theorem: d² = l² + b² = 8² + 6² = 64 + 36 = 100. Step 3: d = √100 = 10 cm.