Chapter 5 - Relationships Within Triangles - 5-5 Indirect Proof - Practice and Problem-Solving Exercises - Page 320: 10

An equilateral triangle cannot be a right triangle because in an equilateral triangle, all angles have to be the same, but in a right triangle, one angle has to be a right angle and the other angles have to be acute. Therefore, statements I and II contradict each other.

An equilateral triangle cannot be a right triangle because in an equilateral triangle, all angles have to be the same, but in a right triangle, one angle has to be a right angle and the other angles have to be acute. Therefore, statements I and II contradict each other.