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`Math Open Reference
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`Acute angle
`From Latin: acutus - "sharp, pointed"
`Definition: An angle whose measure is less than 90°
`Try this Adjust the angle below by dragging an orange dot and see how the angle ∠ABC
`behaves. Note that it is acute for all angles from zero to (but not including) 90°
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`Acute angles are the smallest, being between (but not including) zero and 90° Note also
`that acute triangles are those where all the interior angles are acute.
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`A way to remember
`Sometimes we can confuse acute and obtuse angles. A way to remember is that small
`things tend to be cute. Acute angle is the smallest type.
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`Types of angle
`Altogether, there are six types of angle as listed below. Click on an image for a full
`description of that type and a corresponding interactive applet.
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`Acute angle
`Less than 90°
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`Right angle
`Exactly 90°
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`Obtuse angle
`Between 90° and 180°
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`http://www.mathopenref.com/angleacute.html
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`Ex. 3001
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`Acute Angle definition - Math Open Reference
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`Straight angle
`Exactly 180°
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`Reflex angle
`Between 180° and 360°
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`Full angle
`Exactly 360°
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`Other angle topics
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`General
`Angle definition
`Degrees
`Radians
`Angle bisector
`Subtended angle
`Interior of an angle
`Included angle
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`Angle Types
`Acute angle
`Right angle
`Obtuse angles
`Straight angle
`Reflex angle
`Full angle
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`Angle relationships
`Vertical angles
`Complementary angles
`Supplementary angles
`Linear pair
`Adjacent angles
`Corresponding angles
`Alternate interior angles
`Alternate exterior angles
`Interior angles of a transversal
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`http://www.mathopenref.com/angleacute.html
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`Ex. 3001
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`Acute Angle definition - Math Open Reference
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`Exterior angles of a transversal
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`http://www.mathopenref.com/angleacute.html
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`Ex. 3001