Photographic polyhedron

Solution: There are 24 vertices, each vertex has 3 sides, and two points determine a straight line, which is 24x3÷2=36 sides.

Let the total number of faces be f.

24+F-36=2

F=36-24+2

F= 14

x+y= 14

analyse

According to Euler's formula, the number of vertices+the number of faces-the number of edges =2, and then the number of edges is expressed, and the number of faces can be obtained.

On any positive spherical graph, if R is used to record the number of regions, V is used to record the number of vertices, and E is used to record the number of boundaries, then R+V-E=2, which is euler theorem? , it is 1640 by? Descartes first gave the proof, and later Euler independently gave the proof in 1752, which we call euler theorem.

R+V-E=2 is Euler's formula.

Extended data:

1, understand the meaning of the question: understand the content of the application question and know the conditions and problems of the application question. When reading a question, read, think and understand the meaning of every sentence in the question without losing words or adding words. You can also repeat the conditions and questions to help you understand the meaning of the questions.

2. Choosing algorithm and formula calculation: this is the central work to solve application problems. Starting with what to say and ask, according to the given conditions and questions, and connecting with the significance of four operations, this paper analyzes the quantitative relationship, determines the algorithm, answers and marks the correct unit name. ?

3. Check: check according to the conditions and problems of the application questions to see if the listed formulas and calculation processes are correct and conform to the meaning of the questions. If mistakes are found, correct them immediately.