If the number of faces of a prism is 12 and the number of edges is 30, then the number of vertices of the prism is 12______ ．

If the number of faces of a prism is 12 and the number of edges is 30, then the number of vertices of the prism is 12______ ．

∵ the relationship among vertex number V, face number f and edge number e of a simple polyhedron is: V + F-E = 2, the face number of a prism is 12, and the edge number is 30, then the vertex number is: V + 12-30 = 2, and the solution is: v = 2. So the answer is: 20

If the number of faces of a prism is 12 and the number of edges is 30, then the number of vertices of the prism is 12______ ．

∵ the relationship among vertex number V, face number f and edge number e of a simple polyhedron is: V + F-E = 2, the face number of a prism is 12, and the edge number is 30, then the vertex number is: V + 12-30 = 2, and the solution is: v = 2. So the answer is: 20

Why is the vertex number + face number - edge number of all polyhedrons = 2

It is proved by mathematical induction,
Suppose the formula of n-facet is true, then n + 1-facet can be regarded as cutting a vertex of n-facet into a face. The new surface hypothesis is x-polygon, the number of fixed points + X-1, edge + X, face + 1. The formula is still true

There is a convex polyhedron with 12 edges and 6 vertices. What is the polyhedron

8 sides
And every side is a triangle

When the clock is 1:45, what is the obtuse angle between the minute hand and the hour hand______ &Degree

(360 °△ 60) × [20 + (5 △ 60) × 45], = 6 °× [20 + 112 × 45], = 6 °× [20 + 3.75], = 6 °× 23.75, = 142.5 ° A: the obtuse angle formed by the minute hand and the hour hand is 142.5 & nbsp; degrees

Uncle Zhang bought eight tickets for Avatar. The unit price of class a tickets is 88 yuan, which is 35 yuan more expensive than class B tickets. The total cost is 599 yuan. How many tickets did Uncle Zhang buy for class A and class B tickets?
Simuwu square tripod is the largest bronze ware found in the world. It has a rectangular belly, two straight ears on the top (only one ear was left when it was found, and the other one was later copied and supplemented), and four cylindrical tripods on the bottom. The tripod was made by the son of King Wuding of Shang Dynasty to sacrifice to his mother and relatives. It weighs about 832kg, The mass ratio of copper, tin and lead is about 30:4:1. How many kilogrammes of copper and tin does the tripod contain? (keep the whole number) two questions need to be solved

(1) A: 5 tickets, B: 3 tickets, if a ticket is x, then B ticket is (8-x). B ticket = 88-35 = 53 yuan equation: 88x + 53 (8-x) = 59935x + 424 = 59935x = 175x = 5, then B ticket: 8-5 = 3 tickets (2) copper = 832 △ 30 (30 + 4 + 1) × 30 = 832 △ 35 × 30 = 24960 △ 35 ≈ 713kg tin = 832 △ 30 + 4 + 1

Xiaoming's mother is going to lead Xiaoming and some children of his relatives to form a tour group to travel in the summer. The promotion method of travel agency a is "one adult who leads the group will buy a full ticket, and the rest of the children will get a half price discount on group tickets"; the promotion method of travel agency B is "all adults including the group will get a 60% discount on the full ticket price". If the service quality of the two travel agencies is the same (1) when the number of children is the same, the total charge of the two travel agencies is the same? (2) Discuss which travel agency is more favorable in terms of the number of children

(1) If the number of children is x, the total number of charges of two travel agencies is the same, the total number of charges of a travel agency is 240 + 120x, the total number of charges of B travel agency is (x + 1) × 240 × 0.6. If the two travel agencies have the same charges, then: 240 + 120x = (x + 1) × 240 × 0.6

A company originally planned to install 1600 computers in nuogan days, but in actual installation, the number of computers installed per day was 25% more than the original plan, thus completing the task four days ahead of the schedule. How many computers were originally planned to be installed per day? How many days were originally planned?

The original plan is to install x computers every day;
1600/(x*(1+0.25))=1600/x-4;
The solution is x = 80
So the original plan is to install 80 computers a day, the original plan (1600 / 80) = 20 days

What is 174 divided by and the remainder is 2

174 divided by 43 is four and two
174 divided by 86 is two and two
174 divided by 4 is 43 plus 2

() 6 () () divided by 3 () is equal to 4 (). How to calculate the remainder 24

1608 divided by 33 equals 48 odd 241608 divided by 36 equals 44 odd 241615 divided by 37 equals 43 odd 241620 divided by 38 equals 42 odd 241622 divided by 34 equals 47 odd 241623 divided by 39 equals 41 odd 241634 divided by 35 equals 46 odd 241641 divided by 33 equals 49 odd 241644 divided by 36 equals 45 odd 241652 divided by 37 equals 44 odd 24