Ma'am you missed out the Graphs

4 votes

Two graphs A and B are shown below: Which one of the following statements is true?

- Both A and B are planar
- Neither A nor B is planar
- A is planar and B is not
- B is planar and A is not

3 votes

Best answer

0 votes

Constructing planar version of given graph is quite time consuming. We can solve such questions quickly using the relation :

If E is the number of edges and V is the number of vertices, and **E<= 3(V-2)**, graph is planar, otherwise it is Not Planar.

- A) V=4; E=6; 3*(V-2)=3(4-2)=6=E //Planar
- B) V=8; E=12 3*(V-2)=3(8-2)=18 E=12<18 //Planar

answer : Both A and B are planar