Which of the following statements is not correct?
An angle which is greater than 180∘ but less than 360∘ is called a reflex angle.
An angle greater than 0∘ but less than 90∘ is called an acute angle.
If the sum of two angles is 90∘, then they are called supplementary angles.
An angle greater than 90∘ but less than 180∘ is called an obtuse angle.