math 3

• the sum of interior angles in an n-gon is

  180(n-2)
• the sum of exterior angles in an n-gon is

  360
• the measure of each interior angle in a regular n-gon is

  180(n-2)/n
• the measure of each exterior angle in a regular n-gon is

  360/n
• the number of diagonals in a polygon is

  n(n-3)/2
• acute angles

  0-90 deg
• right angles

  exactly 90 deg
• obtuse angles

  bet. 90 and 180 deg
• adjacent angles


  common vertex, common ray
• linear pair


  share a common ray; non-common rays are opposite rays
• vertical angles


  nonadjacent angles; formed by 2 intersecting lines; same vertex, no common ray
• complementary angles


  2 angles with a sum of 90 deg; <a is complement of <b
• supplementary angles


  2 angles with a sum of 180 deg; <a is supplement of <b
• perpendicular lines


  2 intersecting lines that form right angles
• theorems

  1. an angle is congruent to itself
  2. right and vertical angles are congruent
  3. if 2 angles form linear pair, they are supplementary
  4. a line perpendicular to a given line through a given point is unique
• parallel lines

  dont intersect (NEVAHHH)
• transversals

  line that intersects two lines at diff points
• corresponding angles


  pair (one interior, one exterior) both on the same side of the transversal
• alternate interior


  both interior, opposite sides (criss-cross)
• alternate exterior


  both exterior angles, opposite sides
• all corresponding, alternate interior/exterior angles are

  congruent
• interior and exterior angles on the same side of transversal are

  supplementary
• triangle


  closed figure formed by three segments
• scalene triangle


  NO two sides are congruent
• isosceles


  exactly two sides are equal
• equilateral


  ALL sides are equal
• acute triangles


  has 3 acute angles
• right triangles


  has one right angle and two acute angles
• obtuse triangle


  has one obtuse angle and two acute angles
• equiangular triangle


  all angles are equal
• sum of all angles in a triangle

  180 deg
• each angle in an equiangular triangle measures

  60 degs
• acute angles of a right triangle are

  complementary
• polygon


  closed figure made up of two segments (which intersect at a vertex)
• regular polygon


  all sides and angles are equal
• perimeter


  sum of the length of all its sides
• diagonal


  segment whose endpoints are non consecutive vertices
• which shape has no diagonal?

  triangle
• 3 sides

  triangle
• 4 sides

  quadrilateral