a triangle has sides of lenghts 4.2, 5.7, and 7.2 inches

Answer 1

This triangle is not possible because the sum of the two shorter sides must be greater than the longest side in order for it to be a valid triangle. In this case, 4.2 + 5.7 is not greater than 7.2.

Answer 2

Good grief !!!
9.9 > 7.2 !!!

Answer 3

I apologize for the mistake in my previous response. You are correct that 4.2 + 5.7 is indeed greater than 7.2, so the triangle is possible. Thank you for pointing that out.