Point P is in the interior of ∠AOB. Point Q is in the exterior of ∠AOB. Point A, B and O are on the ∠AOB. 



Acute angle  An angle lies between 0^{0} and 90^{0} 
Right angle  Whose measure is exactly 90^{0} 
Obtuse angle  An angle whose measure is greater than 90^{0} and less than 180^{0} 
Straight angle  Whose measure is exactly 180^{0} 
Reflex angle  An angle whose measure is greater than 180^{0} 