If the sum of two angles is 180 degrees ie, if they form a straight line , the two angles are supplementary.
Each angle is called the supplement of each other.
If the sum of two angles is 90 degrees.
Angles larger than two right angles but less than a full circle (between 180° and 360°) are called reflex angles.
Those angles whose measure is less than 90 degrees
Those angles whose measure is greater than 90 degrees but less than 180 degrees.
If two supplementary angles are equal, they are both right angles.
A right angle is half of a straight line and measures exactly 90 degrees.
When two lines intersect, four angles are formed.
Adjacent angles are supplementary and vertical angles are equal.
Two angles opposite each other, formed by two intersecting straight lines that form an "X"-like shape, are called vertical angles or opposite angles. These angles are equal in measure.
Has its sides lying along a straight line and equal to 180 degrees.
Angles that share a common vertex and edge but do not share any interior points are called adjacent angles.
Parallel Lines and Transversals:
A transversal (line t) across parallel lines form four equal acute angles and four equal obtuse angles.
The top line (line l) is parallel to the bottom line (line m) and line t is the transversal.
Angles 1, 2, 5 and 8 are all equal and acute.
Angles 3, 4, 6 and 7 are all equal and obtuse.
In addition, each of the acute angles is supplementary to each of the obtuse angles. Angles 1 and 4 are supplementary, as are 2 and 3, 2 and 6, and so on.