Calculate the area of pentagons and hexagons
Calculate:
Find the area of a regular pentagon with side length 5 cm.
Your Progress:
Area = (5 × s² × cot(π/5)) ÷ 4
Area = (5 × s² × 1.376) ÷ 4
Area ≈ 1.72 × s²
Where s = side length
Area = (6 × s² × cot(π/6)) ÷ 4
Area = (6 × s² × 1.732) ÷ 4
Area ≈ 2.598 × s²
Where s = side length
Area = (5 × s × a) ÷ 2
Where s = side length, a = apothem
Area = (6 × s × a) ÷ 2
Where s = side length, a = apothem
Area = (5 × r² × sin(2π/5)) ÷ 2
Where r = radius (distance from center to vertex)
Area = (6 × r² × sin(2π/6)) ÷ 2
Area = (3 × √3 × r²) ÷ 2
Where r = radius (distance from center to vertex)
Find the area of a regular pentagon with side length 6 cm.
Solution:
Area = 1.72 × s²
Area = 1.72 × 6²
Area = 1.72 × 36
Area = 61.92 cm²
Find the area of a regular hexagon with side length 4 cm.
Solution:
Area = 2.598 × s²
Area = 2.598 × 4²
Area = 2.598 × 16
Area = 41.57 cm²
Find the area of a regular pentagon with side length 8 cm and apothem 5.5 cm.
Solution:
Area = (5 × s × a) ÷ 2
Area = (5 × 8 × 5.5) ÷ 2
Area = (220) ÷ 2
Area = 110 cm²
Find the area of a regular hexagon with radius 7 cm.
Solution:
Area = (3 × √3 × r²) ÷ 2
Area = (3 × 1.732 × 7²) ÷ 2
Area = (3 × 1.732 × 49) ÷ 2
Area = 127.3 cm²
For regular pentagons, you can use the approximation:
Area ≈ 1.72 × s²
For regular hexagons, you can use:
Area ≈ 2.6 × s²
These approximations are accurate enough for most calculations.
For a regular pentagon:
- Apothem ≈ 0.688 × side length
- Radius ≈ 0.851 × side length
For a regular hexagon:
- Apothem = 0.866 × side length
- Radius = side length
For any regular polygon with n sides:
Area = (n × s × a) ÷ 2
Where n = number of sides, s = side length, a = apothem
This works for both pentagons (n=5) and hexagons (n=6).
If you know multiple measurements, calculate the area using different formulas to verify your answer.
For example, if you know both the side length and apothem of a hexagon, calculate the area using both the s² formula and the (n×s×a)÷2 formula.