The formula of base area of cone

The formula of base area of cone

Base area = square of radius times pi

The calculation formula of cone area is as follows:

The expanded side view of a cone is fan-shaped, and the bottom surface is circle. The surface area is calculated as fan-shaped area = 1 / 2 * (arc length of fan-shaped) * (generatrix length of cone) + bottom surface area
The sector arc length is the perimeter of the bottom circle, and the cone generatrix is the sector radius

The circumference of a circle is 12.56 meters. Find the length of the radius
Who told you I graduated

12.56 divided by π and divided by 2

The circumference of a semicircle is 12.56 meters. What's the radius?

The length of semicircle arc is π R
The diameter is 2R
So the girth 2R + π r = 12.56m
R = 12.56 / (π + 2) ≈ 2.443m

The sum of the radii of the two circles is 3 decimeters. It is known that the perimeter of the big circle is 12.56 decimeters, and that of the small circle is 3 decimeters______ What is the area of a small circle in decimeter______ ．

Radius of big circle: 12.56 △ 3.14 △ 2 = 2 (decimeter), radius of small circle: 3-2 = 1 (decimeter), perimeter of small circle: 2 × 3.14 × 1 = 6.28 (decimeter), area of small circle: 3.14 × 12 = 3.14 × 1 = 3.14 (square decimeter); answer: perimeter of small circle is 6.28 decimeter, area of small circle is 3.14 square decimeter

The circumference of a semicircle is 15.42cm, its radius is (), and its area is (). [to calculate the process]

The circumference of a semicircle is 15.42cm, its radius is (3cm), and its area is (14.13cm2). [analysis]: let the radius of the semicircle be RCM, then according to the semicircle's circumference = half of the circle's circumference + 2R, the equation is listed to calculate the radius, and then the area of the semicircle is obtained. [solution]: let the radius of the semicircle be r

If the radius of a circle increases by 2 cm, the circumference of the circle increases______ Cm

Let the radius of a circle be 2 cm, and the increased radius be (2 + 2) cm, then the original perimeter = 2 × 3.14 × 2 = 3.14 × 4 = 12.56 (CM); the current perimeter: 2 × 3.14 × (2 + 2) = 3.14 × 8 = 25.12 (CM); the increased perimeter: 25.12-12.56 = 12.56 (CM); answer: the radius of a circle is increased by 2 cm, and the perimeter is increased by 12.56 cm

The sum of the circumference and diameter of a circle is 16.56 cm. How many square centimeters is the area of the circle!

16.56 △ 3.14 + 1) △ 2 = 2cm
Area: 3.14 × 2 & # 178; = 12.56 square centimeter

The area of a circle is 6.28 square centimeters. What is the circumference, diameter and radius of the circle

Radius of circle = √ (6.28 △ 3.14) = √ 2 (CM)
Diameter of circle = 2 √ 2 (CM)
Circumference of circle = 2 π √ 2 (CM)

The sum of the circumference, diameter and radius of a circle is 9.28. What's the diameter and area of a circle

Take the radius as 1 part, the diameter has such 2 parts, and the circumference has such 3.14 * 2 = 6.28 parts
So the radius is 9.28 / (1 + 2 + 6.28) = 1
So the diameter is 1 * 2 = 2
The perimeter is 3.14 * 1 * 2 = 6.28
The area is 1 * 1 * 3.14 = 3.14