Vocabulary Review
supplementary – the angles add up to 180 degrees.
e.g. Angles x and y are supplementary. If angle x is 56 degrees, what is the measure of angle y?
- ans: y = 180 – 56 = 124 degrees.
linear pair – two angles that are next to each other on a straight line; are always supplementary.
complementary – the angles add up to 90 degrees.
e.g. Angles x and y are complementary. If angle y is 73 degrees, what is the measure of angle x?
- ans: x = 90 – 73 = 17 degrees
vertical – the angles are opposite each other; are congruent.
alternate interior angles – angles found between two parallel lines on opposite sides of a third line that intersects these parallel lines (transversal); are congruent.
alternate exterior angles – angles found outside two parallel lines that are on opposite sides of the transversal; are congruent.
corresponding angles – angles on the same side of the transversal; one is outside and one is inside; are also congruent.
midpoint – the exact middle of a line segment.
e.g. C is the midpoint of AB. If AC is equal to 4, what is the length of AB?
- ans: AC and CB are equal in measure because C is the midpoint. Therefore, AB is equal to 8.
bisect – to cut into two equal halves. If a 84 degree angle is bisected, that means a line is drawn through the angle that splits it into two 42 degree angles.
Example Problems
A Problem Involving a Linear Pair
A Problem Involving Vertical Angles
A Problem Involving Parallel Lines
A Problem Involving Midpoint
