The central angle of the sector is unchanged, the radius is reduced to one third of the original, and the area of the sector is reduced to the original_____ .

The central angle of the sector is unchanged, the radius is reduced to one third of the original, and the area of the sector is reduced to the original_____ .

The formula of sector area is s = & * r * r / 2, where & is the center angle of the circle. If the center angle of the circle remains unchanged, the radius becomes one third of the original, and the area becomes one ninth of the original according to the formula

If the central angle of a sector is expanded by three times and the radius length is reduced by 13, then the ratio of the sector area to the original sector area is ()
A. 1B. 3C. 9D. 13

Original sector area = center angle △ 360 °× π × radius 2, new sector area = (center angle × 3) △ 360 °× π × 13 radius) 2 = center angle △ 360 × 3 × π × 19 radius 2 = center angle △ 360 °× π × radius 2 × 13, so new sector area: original sector area = 13:1 = 13

How to calculate the arc length of an arc? How to find the calculation formula

Radius = 5000
Arc 1 height = 2200
Radius arc 1 height = 2800
Pythagorean about 5000 * 5000-2800 * 2800, after the root
Chord 1 = 4142.463035 * 2 = 8284.926071
In the same way
Arc 2 height = 2200-1000 = 1200
Chord 2 = 3249.615 * 2 = 6499.231
Chord 1, height 1, arc 1
8284.926 2200 9764.105268
Chord 2, height 2, arc 2
6499.231 1200 7074.832118
Arc 1-arc 2 = 2689.273
The arc length you want is 2689.273/2 = 1344.637

A fan-shaped thin sheet iron with an arc length of 18.84 decimeters can form a cone 4 decimeters high. What is the volume of this cone?

The bottom radius of the cone is 18.84 △ 2 △ 3.14 = 3 (decimeter)
The volume of cone is 3.14 × 3 & # 178; × 4 △ 3 = 37.68 (cubic decimeter)
A: the volume of a cone is 37.68 cubic decimeters

A circular iron sheet with radius R is cut off from the center and enclosed into a bottomless cone with a central angle of A. is the volume of the cone expressed as a function of a?

A cylinder is 4 decimeters high, and its volume is 40 cubic decimeters, 10 cubic decimeters more than the volume of a cone with the same base. The height of the cone is______ Decimeter

The bottom area of the cylinder: 40 △ 4 = 10 (square decimeter), (40-10) × 3 △ 10, = 90 △ 10, = 9 (decimeter); answer: the height of the cone is 9 decimeters. So the answer is: 9

The volume of a cone is 314 cubic decimeters. The diameter of its bottom is 10 decimeters. Its height should be ()
A. 4 decimeters B. 12 decimeters C. 24 decimeters

314 × 3 ^ [3.14 × (10 ^) 2], = 942 ^ 78.5, = 12 (decimeter), a: its height is 12 decimeters

A circle can be divided into several sectors. What is a sector made up of and what passes through it?

The circle can be divided into several sectors. The sector is a figure composed of an arc and two radii of the line passing through the two ends of the arc and the center of the circle

What figure does a cone consist of? What I wrote is that a sector plus a circle is wrong
The teacher said that it was the development of what surface

A cone is composed of a side (curved surface) and a bottom (circle)

I want to make a cone expansion. How to make a fan?

First cut a fan, surround it, add a bottom (circle) or compare it with a cone