geo vocab

Point

A location with no size or dimension.

Line

A straight path that extends infinitely in both directions.

Line Segment

A part of a line with two endpoints.

Ray

A part of a line that starts at one point and extends forever in one direction.

Plane

A flat surface that extends infinitely in all directions.

Angle

Formed by two rays with a common endpoint (vertex).

Acute Angle

An angle that is less than 90°.

Right Angle

An angle that is exactly 90°.

Obtuse Angle

An angle that is greater than 90° but less than 180°.

Straight Angle

An angle that is exactly 180°.

Complementary Angles

Two angles that add up to 90°.

Supplementary Angles

Two angles that add up to 180°.

Vertical Angles

Angles opposite each other when two lines cross (always equal).

Adjacent Angles

Angles that share a side and a vertex.

Parallel Lines

Lines that never intersect and are always the same distance apart.

Perpendicular Lines

Lines that intersect at a 90° angle.

Transversal

A line that intersects two or more lines.

Polygon

A closed figure made of straight lines.

Triangle

A polygon with 3 sides.

Equilateral Triangle

A triangle where all sides and angles are equal.

Isosceles Triangle

A triangle with two sides and two angles equal.

Scalene Triangle

A triangle with no sides or angles equal.

Right Triangle

A triangle that has one 90° angle.

Quadrilateral

A polygon with 4 sides.

Parallelogram

A quadrilateral with opposite sides parallel and equal.

Rectangle

A quadrilateral with all angles 90°, opposite sides equal.

Square

A quadrilateral where all sides and angles are equal (90°).

Rhombus

A quadrilateral where all sides are equal, opposite angles are equal.

Trapezoid

A quadrilateral with one pair of parallel sides.

Perimeter

The distance around a shape.

Area

The space inside a shape.

Volume

The amount of space inside a 3D object.

Circumference

The distance around a circle.

Radius

Distance from the center of a circle to the edge.

Diameter

Distance across a circle through the center.

Pi (π)

A constant approximately equal to 3.14 used in circle calculations.

Translation

Sliding a shape without rotating or flipping it.

Rotation

Turning a shape around a point.

Reflection

Flipping a shape over a line (mirror image).

Dilation

Making a shape larger or smaller while keeping its shape.

Congruent

Exactly the same shape and size.

Similar

Same shape but different sizes (angles stay the same).

Hypotenuse

The longest side of a right triangle (opposite the right angle).

Pythagorean Theorem

In a right triangle: a^2 + b^2 = c^2.

Tessellation

A pattern of shapes that fit perfectly together without gaps.