Geometry basics

Net diagram

A 2d pattern that you can fold to form a 3d figure shows all surfaces in one view

orthographic drawing

the top view, front view, and right view of a 3D figure

Isometric

A form of pictorial drawing in which all three drawing axes form equal angles of 120 degrees with the plane of projection.

point -

A location in space. shown with capital letter

line

a straight path that extends without end in opposite directions

named by points on line or lowercase letter

plane

- flat surface named with capital letter or three letters on plane

segment

- part of a line with two endpoints

ray

- a part of a line that starts at an endpoint and extends forever in one direction

opposite ray

• two rays that have a common endpoint and form a line

colinear points -

points that lie on the same line

coplanar

• points that lie on the same plane

space -

the set of all points

postulate -

a statement that is accepted as true without proof

intersection

• A point where lines intersect.

congruence

- same size and shape

midpoint

- A point that divides a segment into two congruent segments

Bisector

- a ray that divides an angle into two congruent angles

angle

A figure formed by two rays with a common endpoint

adjacent angle

Angles that have a common side and a common vertex (corner point).

vertical angles -

A pair of opposite congruent angles formed by intersecting lines

complementary angles -

Two angles whose sum is 90 degrees

supplementary angles -

Two angles whose sum is 180 degrees

Linear pair -

A pair of adjacent angles whose noncommon sides are opposite rays form straight line.

Midpoint formula on a number line -

M=a+b/ 2

Midpoint formula on a coordinate plane -

(x₁+x₂)/2, (y₁+y₂)/2

square area -

s²

triangle area -

1/2bh

rectangle area -

Bh

circle area -

πr²

circumference

- 2πr

diameter

- A straight line passing from side to side through the center of a circle or sphere.

radius formula

- r=d/2

Distance Formula -

d = √[( x₂ - x₁)² + (y₂ - y₁)²]