Question

If a triangle is obtuse, then all angles do not measure less than 90°.

Which of these is logically equivalent to it?
Answer
If a triangle is not obtuse, then all angles measure less than 90°.
If a triangle is obtuse, then it has no angle measuring more than 90°.
If all angles of a triangle measure less than 90°, then the triangle is not obtuse.
If all angles of a triangle do not measure less than 90°, then the triangle is obtuse.

Answer 1

the third

Answer 2

what he said^

Answer 3

obtuse angle >90 degrees

Answer 4

and if all angles are less than 90 then it cannot be obtuse

Answer 5

\[P \implies Q \iff /Q \implies /P\]This gives the same answer indicated above.