ACT Preparation / Unit 13 ACT 1201 short lesson, about 20 seconds
Angles and Their Measures
Captions available
The idea
An angle is measured in degrees. An acute angle is less than 90°, a right angle exactly 90°, an obtuse angle between 90° and 180°, and a straight angle 180°.
In practice
The hands of a clock at 3:00 form a right angle; at 6:00, a straight angle.
Where people slip
Straight means 180°: two angles that together form a line add to it.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
- Nothing. This is a starting point.
Something wrong in this lesson? Flag it · Sources for ACT Preparation