2. Types of Angles
• Classification
– Acute: all angles are less than 90°
– Obtuse: one angle is greater than 90°
– Right: has one angle equal to 90°
• Complementary: the sum of two angles is 90°
• Supplementary: the sum of two angles is 180°
• Adjacent: angles that share a side
• Linear Pair: angles that are both supplementary
and adjacent
4. Supplementary Angle Pairs
Angles that are both on the same side of
the transversal and either both interior or
exterior
• <3 & <5, <4 & < 6, <1 & <7, <2 & < 8
Linear Pair
• <1 & <2, <2 & <4, <3 & <4, <1 & <3,
<5 & <6, <6 & <8, <7 & <8, <5 & <7
1 2
3 4
5 6
7 8
formed by
Parallel Lines
5. Polygons
• The sum of the interior angles: (n - 2)(180°)
• Classified by number of sides (n)
– Triangle (3)
– Quadrilateral (4)
– Pentagon (5)
– Hexagon (6)
– Heptagon (7)
– Octagon (8)
– Nonagon (9)
– Decagon (10)
• Regular Polygon: all sides are congruent
6. Triangles
• The sum of the angles in a triangle is 180°
• a – b < third side < a + b
• The sum of the two remote interior angles is
equal to the exterior angles
• Types:
Scalene Isosceles Equilateral Right
Two
sides are equal One
Right angle
All
sides are equal
No sides
are equal
7. QUADRILATERALS
PARALLELOGRAM
Both pairs of opposite
sides are parallel
TRAPEZOIDS
Only one pair of
Opposite sides parallel
ISOSCLES
TRAPEZOID
A trapezoid that has
two equal sides
ROMBUS
4 equal sides
RECTANGLE
4 right angles
SQUARE
Both a rhombus
and a rectangle
8. Properties of Parallelograms
Diagonals are
perpendicular to each other
Diagonals
bisect their angles
Diagonals bisect each other
Opposite sides are congruent
Opposite angles are congruent
Diagonals bisect each other
Consecutive angles are supplementary
Diagonals form two congruent triangles
Diagonals are
congruent to each other
