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Grade 7 Chapter 7
Foundations for Geometry
Question | Answer |
---|---|
acute angle | An angle that measures less than 90 degrees. |
acute triangle | A triangle with all angles measuring less than 90 degrees. |
angle | A figure formed by two rays with a common vertex. |
center of rotation | The point about which a figure is rotated. |
complementary angles | Two angles whose measures add up to 90 degrees. |
congruent | Having the same size and shape. |
correspondence | The relationship between two or more objects that are matched. |
equilateral triangle | A triangle with three congruent sides. |
image | A figure resulting from a transformation. |
isosceles triangle | A triangle with at least two congruent sides. |
line | A straight path that extends without end in opposite directions. |
line of symmetry | the imaginary "mirror" in line symmetry. |
line symmetry | One half of a figure is a mirror image of the other half. |
obtuse angle | An angle whose measure is greater that 90 degrees but less than 180 degrees. |
obtuse triangle | A triangle containing one obtuse angle. |
parallel lines | Lines in a plane that do not intersect. |
parallelogram | A quadrilateral with two pairs of parallel sides. |
perpendicular lines | Lines that intersect to form right angles. |
plane | A flat surface that extends forever. |
point | An exact location in space. |
polygon | A close plane figure formed by three or more line segments that intersect only at their endpoints. |
ray | A part of a line that starts at one endpoint and extends forever. |
rectangle | A parallelogram with four right angles. |
reflection | A transformation of a figure that flips the figure across a line. |
regular polygon | A polygon with congruent sides and angles. |
regular tessellation | A regular polygon is repeated to fill a plane. |
rhombus | A parallelogram with all sides congruent. |
right angle | An angle that measures 90 degrees. |
right triangle | A triangle containing a right angle. |
rise | The vertical change when,the slope of a line is expressed as the ratio rise/run, or "rise over run". |
rotation | A transformation in which a figure is turned around a point. |
rotational symmetry | When a figure can be rotated less than 360 degrees around a central point and coincides with the original figure. |
run | The horizontal change when,the slope of a line is expressed as the ratio rise/run, or "rise over run". |
scalene triangle | A triangle with no congruent sides. |
segment | A part of a line between two endpoints. |
slope | A measure of the steepness of a line on a graph; the rise divided by the run. |
square | A rectangle with four congruent sides. |
supplementary angles | Two angles whose measures have a sum of 180 degrees. |
tessellation | A repeating pattern of plane figures that completely cover a plane with no gaps or overlaps. |
transformation | A change in the size or position of a figure. |
translation | A movement (slide) of a figure along a straight line. |
transversal | A line that intersects two or more lines. |
trapezoid | A quadrilateral with exactly one pair of parallel sides. |
Triangle Sum Theorem | The measures of the angles in a triangle add up to 180 degrees. |
vertical angles | A pair of opposite congruent angles formed by intersecting lines. |