Question | Answer |
perimeter | the distance around a figure |
area | the space a figure encloses |
line | extends forever in two directions |
ray | a part of a line; extends forever in one direction and has one endpoint |
line segment | a part of a line |
angle | two rays with a common endpoint |
vertex | the common endpoint of an angle |
acute angle | an angle that measures less than 90 degrees |
right angle | an angle that measures exactly 90 degrees |
obtuse angle | an angle that measures more than 90 degrees and less than 180 degrees |
straight angle | an angle that has a measure of exactly 180 degrees; it is a line |
protractor | a tool used to measure angles |
complementary angles | two angles that add up to 90 degrees |
supplementary angles | two angles that add up to 180 degrees |
congruent | when two figures have the same shape and the same size |
bisect | divides a figure into two equal parts |
plane | an infinite, flat surface |
parallel | lines that never meet |
transversal | a line that intersects two or more parallel lines |
midpoint | the point that divides a line segment into two equal segments |
perpendicular | lines, rays, and line segments that form right angles |
quadrilateral | four-sided figure |
parallelogram | quadrilateral with two pairs of parallel sides and two pairs of congruent sides |
rectangle | quadrilateral; parallelogram; has four right angles |
square | quadrilateral; parallelogram; rectangle; rhombus; has four right angles and four congruent sides |
rhombus | quadrilateral; parallelogam; has four congruent sides |
trapezoid | quadrilateral; has only one pair of parallel sides |
polygon | a geometric figure with at least three sides |
triangle | a polygon with three sides |
pentagon | a polygon with five sides |
hexagon | a polygon with six sides |
octagon | a polygon with eight sides |
regular polygon | a polygon where all of the sides and all of the angles are equal |
(n - 2)180 | formula to find the sum of the measures of the angles; n is the number of sides of the polygon |
perfect square | the square of a whole number |
square root | the length of the side of a square with an area equal to the number |
hypotenuse | in a right triangle, the side opposite the right angle; it is the longest side |
legs | the two sides of the right triangle (NOT the hypotenuse) |
pythagorean theorem | formula used to find a missing length of a right triangle; the sum of the squares of athe legs of a right triangle is equal to the square of the hypotenuse |
area of a triangle | one half the product of the lengths of the base and the height |
area of a parallelogram | the product of its height and the length of its base |