The perimeter of a quarter circle is 2 radii plus a quarter of the circumference of the whole circle: → 2 × radius + ¼ × 2 × π × radius = 32.13 cm → radius × (2 + π/2) = 32.13 cm → radius = 32.13 ÷ (2 + π/2) cm ≈ 9.00 cm
A circle with a radius of 40 cm has an area of 5,026.55 square cm.
The side of the square is equal to the diameter of the circle, in this case 2a so the perimeter is 8a cm.
Normally, the amount of the side of the rectangle below the quarter circle on it would expected to be calculated. However, the radius of the circle equals the amount that is subtracted, but in calculating the perimeter it has to be added back in again as it forms part of the perimeter. Thus the perimeter is the perimeter of the rectangle plus a quarter of the circumference of the circle. → perimeter = 2 × (20cm + 2 cm) + ¼ × 2 × π × 11 cm ≈ 44 cm + 3.14 × 11/2 = 61.27 cm.
There are an infinite number of shapes with an area of 16 square centimetres. The one with the smallest perimeter is a circle of radius 2.2568 cm (to 4 dp). Such a circle will have a perimeter of 14.1796 cm. This value for the perimeter can be increased by changing the circle into an ellipse: making the ellipse flatter and longer (increasing its eccentricity) so that the perimeter increases without changing the area. There is no upper bound to the perimeter. This can also be done for quadrilaterals, with the smallest one being a 4cm x 4cm square. But you could have a rectangle with sides 0.4 cm and 40 cm and a perimeter of 80.8 or 0.04 cm and 400 cm and a perimeter of 800.08 cm or 0.004 cm and 4000 cm and a perimeter of 8000.008 cm and so on - without limit. Or you could have triangles, or polygons with 5 or more sides. The important point is that area does not determine the perimeter.
The circumference of a circle with a radius of 5cm is: 31.42 cm
The perimeter of a quarter circle is 2 radii plus a quarter of the circumference of the whole circle: → 2 × radius + ¼ × 2 × π × radius = 32.13 cm → radius × (2 + π/2) = 32.13 cm → radius = 32.13 ÷ (2 + π/2) cm ≈ 9.00 cm
The radius measures from the center of the circle to the perimeter (outside), so if the radius is 8.5 cm that would make the diameter of the circle 17 cm. (8.5 cm X 2 = 17 cm)
The radius is 5.00 cm.
A circle with a radius of 40 cm has an area of 5,026.55 square cm.
Pi= 3.1416 circle / 3.1416=diameter
The side of the square is equal to the diameter of the circle, in this case 2a so the perimeter is 8a cm.
The perimeter is pi*r + 2r = 92.6 cm
The perimeter of a circle is equal to pi times the diameter, so for a circle with a diameter of 14 cm, multiply by pi, which is approximately 3.14, and you get 43.96 cm, which for most purposes you could round off to 44 cm.
Normally, the amount of the side of the rectangle below the quarter circle on it would expected to be calculated. However, the radius of the circle equals the amount that is subtracted, but in calculating the perimeter it has to be added back in again as it forms part of the perimeter. Thus the perimeter is the perimeter of the rectangle plus a quarter of the circumference of the circle. → perimeter = 2 × (20cm + 2 cm) + ¼ × 2 × π × 11 cm ≈ 44 cm + 3.14 × 11/2 = 61.27 cm.
There are an infinite number of shapes with an area of 16 square centimetres. The one with the smallest perimeter is a circle of radius 2.2568 cm (to 4 dp). Such a circle will have a perimeter of 14.1796 cm. This value for the perimeter can be increased by changing the circle into an ellipse: making the ellipse flatter and longer (increasing its eccentricity) so that the perimeter increases without changing the area. There is no upper bound to the perimeter. This can also be done for quadrilaterals, with the smallest one being a 4cm x 4cm square. But you could have a rectangle with sides 0.4 cm and 40 cm and a perimeter of 80.8 or 0.04 cm and 400 cm and a perimeter of 800.08 cm or 0.004 cm and 4000 cm and a perimeter of 8000.008 cm and so on - without limit. Or you could have triangles, or polygons with 5 or more sides. The important point is that area does not determine the perimeter.
If it is a 7.1 cm radius circle, then its radius is exactly 7.1 cm!