Geometry 1

Page 1

question answer

parallel lines: Parallel lines are always the same distance apart, and will never touch.

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perpendicular lines: Perpendicular lines meet or cross to form right (90 degrees) angles.

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straight angles: Straight angles are also known as straight lines, and measure 180 degrees.

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acute angle: An acute angle measures more than 0 degrees, but less than 90 degrees.

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obtuse angle: An obtuse angle measures more than 90 degrees, but less than 180 degrees.

right angle: A right angle measures exactly 90 degrees. Right angles are sometimes called "square corners", because they look like the corners of a square or a rectangle.

triangle: A triangle is a polygon with exactly three sides and three angles.

acute triangle: An acute triangle is a triangle whose three angles are ALL acute angles (less than 90 degrees).

obtuse triangle: A triangle with exactly ONE obtuse angle. (More than one obtuse angle would mean the three angles could not add up to 180 degrees.)

right triangle: A triangle with exactly ONE right angle. (More than one right angle would mean the three angles could not add up to 180 degrees.)

equilateral triangle: A triangle whose three sides are ALL the same length. (Also called an equiangular triangle, because the three angles would also have equal measures.)

isosceles triangle: A triangle with two (or three) sides being equal in length.

scalene triangle: A triangle whose three sides all have different lengths.

quadrilateral: A polygon having exactly four sides and four angles.

parallelogram: A quadrilateral whose opposite sides are both congruent (equal in length) and parallel. Rectangles, squares, and rhombuses (rhombi) are all special types of parallelograms.

rectangle: A parallelogram whose four angles are all right angles.

rhombus: A parallelogram whose four sides are all congruent.

square: A parallelogram whose four sides are all congruent (making it also a rhombus) and whose four angles are all right angles (making it a rectangle).

trapezoid: A quadrilateral with EXACTLY ONE pair of parallel sides - the other pair is NOT parallel, so a trapezoid is not a parallelogram.

pentagon A polygon with 5 sides and 5 angles.

hexagon: A polygon with 6 sides and 6 angles.