Let ABC be an equilateral triangle. How many squares in the same plane as ABC share two vertices with the triangle?

9 squares

Step-by-step explanation:

An equilateral has three equal sides.  You can have two squares on each side: AB, one in which the triangle, ABC, falls within the square and the other where the square does not contain the triangle, ABC.  You can also have two squares on each side - BC, one in which the triangle, ABC, falls within the square and the other where the square does not contain the triangle, ABC.  Again, you can have two squares on each side - CA, one in which the triangle, ABC, falls within the square and the other where the square does not contain the triangle, ABC.  In addition, AB, BC and CA can be a diagonal of squares.  

TL;DR

In conclusion, you have 9 squares in all - 3 as diagonals of squares and 6 as sides of squares. Brainliest appreciated!