Question

Диаметр окружности равен 15 см Найдите длину окружности Ответ запишите в дециметрах и округлите его до единиц

Answer 1

C = 2πr = πD = 15 * 3,14 = 47,1 см.
1 дм = 10 см.
47,1 см = 4,71 дм.
Округляем ≈ 5 дм.
Ответ: 5 дм.

Answer 2

Calculation of the Circumference of a Circle

To find the circumference of a circle, we can use the formula:

C = πd

where C is the circumference and d is the diameter of the circle.

In this case, the diameter of the circle is given as 15 cm. Therefore, we can substitute this value into the formula to find the circumference.

C = π * 15

To calculate the circumference, we need to know the value of π. The value of π is approximately 3.14159.

Substituting the values into the formula, we get:

C = 3.14159 * 15

Calculating this expression, we find that the circumference of the circle is approximately 47.12385 cm.

Converting the Circumference to Decimeters

To convert the circumference from centimeters to decimeters, we need to divide the value by 10, since there are 10 decimeters in a meter.

Dividing the circumference of 47.12385 cm by 10, we get:

C_decimeters = 47.12385 / 10

Calculating this expression, we find that the circumference in decimeters is approximately 4.712385 dm.

Rounding the Circumference to the Nearest Unit

To round the circumference to the nearest unit, we can use the standard rounding rules. If the decimal part is less than 0.5, we round down; if it is 0.5 or greater, we round up.

In this case, the decimal part of the circumference in decimeters is 0.712385. Since this is less than 0.5, we round down.

Therefore, the rounded circumference in decimeters is 4 dm.

So, the length of the circumference of the given circle is approximately 4 decimeters when rounded to the nearest unit.