Area · Grade 9

In Grade 9 you learn: sectors and composite shapes.

Area is the amount of flat space a shape covers, measured in square units such as cm² and m². Count the squares, or use the formula for the shape; a compound shape splits into simpler shapes.

Key facts

• Area is measured in square units: count the squares a shape covers.
• Rectangle: area = length × width; perimeter = 2 × (length + width).
• Triangle: area = ½ × base × perpendicular height.
• Parallelogram: area = base × perpendicular height.
• Trapezoid: area = ½ × (a + b) × h, where a and b are the parallel sides.
• Compound shapes: split into rectangles (or subtract a missing piece). Use the same units throughout.

Worked examples

Other years

• Area · Grade 3
• Area · Grade 4
• Area · Grade 5
• Area · Grade 6
• Area · Grade 7
• Area · Grade 8