<Ul> <Li> Angles smaller than a right angle ( less than 90 ° ) are called acute angles ( `` acute '' meaning `` sharp '' ) . </Li> <Li> An angle equal to 1 / 4 turn ( 90 ° or π / 2 radians ) is called a right angle . Two lines that form a right angle are said to be normal , orthogonal , or perpendicular . </Li> <Li> Angles larger than a right angle and smaller than a straight angle ( between 90 ° and 180 ° ) are called obtuse angles ( `` obtuse '' meaning `` blunt '' ) . </Li> <Li> An angle equal to 1 / 2 turn ( 180 ° or π radians ) is called a straight angle . </Li> <Li> Angles larger than a straight angle but less than 1 turn ( between 180 ° and 360 ° ) are called reflex angles . </Li> <Li> An angle equal to 1 turn ( 360 ° or 2π radians ) is called a full angle , complete angle , or a perigon . </Li> <Li> Angles that are not right angles or a multiple of a right angle are called oblique angles . </Li> </Ul>
<Ul> <Li> Angles smaller than a right angle ( less than 90 ° ) are called acute angles ( `` acute '' meaning `` sharp '' ) . </Li> <Li> An angle equal to 1 / 4 turn ( 90 ° or π / 2 radians ) is called a right angle . Two lines that form a right angle are said to be normal , orthogonal , or perpendicular . </Li> <Li> Angles larger than a right angle and smaller than a straight angle ( between 90 ° and 180 ° ) are called obtuse angles ( `` obtuse '' meaning `` blunt '' ) . </Li> <Li> An angle equal to 1 / 2 turn ( 180 ° or π radians ) is called a straight angle . </Li> <Li> Angles larger than a straight angle but less than 1 turn ( between 180 ° and 360 ° ) are called reflex angles . </Li> <Li> An angle equal to 1 turn ( 360 ° or 2π radians ) is called a full angle , complete angle , or a perigon . </Li> <Li> Angles that are not right angles or a multiple of a right angle are called oblique angles . </Li> </Ul>
an angle that measures greater than 0 degrees and less than 90 degrees
an angle that measures greater than 0 degrees and less than 90 degrees
acute
acute