Basic Geometry Vocabulary Review Plane and Solid Figures

Basic Geometry Vocabulary Review

Plane and Solid Figures • Plane figure – a plane figure has just 2 dimensions – length and width. • Solid figure – a solid figure has 3 dimensions – length, width, and height.

Solid Figures • Face – each flat surface of a solid figure • Edge – a line segment where 2 faces meet on a solid figure. • Vertex – “a corner” – where 3 or more edges meet. The plural form of vertex is “vertices. ”

Solid Figures

Polygons • Polygon – a polygon is a closed plane figure made up of line segments. Each line segment is a side.

Polygons – Know Your Prefixes! • “Tri” – means 3 – a triangle has 3 sides. • “Quad” – means 4 – a quadrilateral has 4 sides. • “Penta” – means 5 – a pentagon has 5 sides. • “Hexa” – means 6 – a hexagon has 6 sides. • “Hepta” – means 7 – a heptagon has 7 sides. • “Octa” – means 8 – an octagon has 8 sides. • “Nona” – means 9 – a nonagon has 9 sides. • “Deca” – means 10 – a decagon has ten sides.

Points, Line Segments, and Rays • Point – an exact location in space. • Line – a straight path of points that goes on and on in two directions. • Line segment – a part of a line. It has 2 endpoints. • Ray – part of a line. It has one endpoint and continues on and on in only one direction.

Angles • Right angle – has a square corner • Acute angle – less than a right angle • Obtuse angle – more than a right angle. • Straight angle – forms a straight line.

Lines • Parallel lines – never intersect. • Intersecting lines – lines that cross through the same point. • Perpendicular lines – lines that form right angles where they intersect each other.

Quadrilaterals • Quadrilaterals can also • Remember , quad be classified (or means 4! So we are grouped) by their angles talking about 4 sided or their pairs of sides! figures!

Rectangle • Rectangle – there are 4 right angles!

Square • Square – there are 4 right angles and all sides are the same length.

Trapezoid • Trapezoid – There is only one pair of parallel sides.

Parallelogram • Parallelogram – opposite sides are parallel.

Rhombus • Rhombus – opposite sides are parallel AND all 4 sides are the same length.

Congruent • Congruent – Same shape and same size. *If items are congruent, they are automatically similar. However, just because items are similar, doesn’t mean they are automatically congruent.

Slide (Translation) • Slide (translation) – moves a figure in a straight direction.

Flip (Reflection) • Flip (reflection) – a figure gives its mirror image.

Turn (Rotation) • Turn (rotation) – moves a figure around a point.

Similar • Similar – same shape, but may or may not have the same size! *If items are congruent, they are automatically similar. However, just because items are similar, doesn’t mean they are automatically congruent.

Symmetry • Symmetry – when a figure can be folded into two congruent halves. *Means one half can lay perfectly over the other half in an exact match. line of symmetry