Review

Standard position

We say that an angle is in standard position when its vertex A is at the origin of the coordinate system, and its Initial side AB lies along the positive x-axis. We say that AB has "swept out" the angle BAC, and that AC is its Terminal side.

Coterminal angles

Angles are coterminal if, when in the standard position, they have the same terminal side.

Acute angle

An angle whose measure is less than 90^o.

Obtuse angle

An angle whose measure is grater than 90^o but less than 180^o.

Right angle

An angle whose measure is 90^o.

Reflex angle

An angle whose measure is greater than 180^o but less than 360^o.

A straight angle

An angle whose measure is 180^o.

Central Angle

A central angle is an angle with endpoints and located on a circle's circumference and vertex located at the circle's center . A central angle in a circle determines an arc . For an inscribed angle and central angle with the same endpoints,