# Glossary

Acute Angle/Triangle

an angle/triangle with an angle smaller than 90°

Allowance

the material needed for a specific component-“We must allow this much extra”. Usually a seam for connection

Apex

the intersection point of a cone, as seen in the elevation view

Arc

a portion of a circumference

Auxiliary Line

an extra element line added, different from the standard divisions

Bisect

to divide in half

Chord

a straight line from 2 points on a circumference

Circumference

the distance around a circle, perimeter of a circle

Diameter

the distance across a circle at center, twice the radius

Elbow Rule

the number of pieces of a round elbow times 2 then minus 2(# of pcs x 2-2) gives us the number of gores in the elbow

Element Line

a line representing an edge or bend

Elevation View

looking at the front or side of something, to have elevation (height), 2D

Frustum

a cone with the top cut parallel to the base

Gore

a part of a round elbow which allows us to calculate the miter angle

Horizontal

a line/plane level with the horizon. Flat, level

Miter

an intersection of 2 pieces- an irregular cut on the end of something

Obtuse Angle/Triangle

an angle/triangle with an angle larger than 90°

Parallel

a line/plane that is equal distance from another

Pattern

the shape of the object, still in 2D form

Perpendicular

a line/plane which is 90° to another

Plan view

looking down at something, a “birds eye view”, “floor plan” (2D)

Point of Tangency

a straight line that touches the circle at only one point

Profile

a half of a plan view, drawn on the outside of an object

a sector which equals one quarter of the area of a circle

the distance from center to any point of the circumference, half the diameter

Right Angle/Triangle

an angle/triangle which has a 90° angle

Sector

the area of a circle bound by 2 radii and an arc

Segment

the area of a circle bound by an arc and a chord

Slant Height (small or large)

the hypotenuse of a cone, outside edge. The slant height is always a true length in the elevation view

Stretch-out

a shape which has been “stretched out”, to take a perimeter and make it straight

Stretch-Out Angle/Arc

the angle or arc which encompasses a radial line pattern

Tangent

a line which touches only 1 point of a circumference

Triangulation from Plan View

the length of an element line, set 90° to the vertical height, gives the true length of that line

True Length

a dimension or line that is not distorted by the view

True Length Diagram (TLD)

a 90° corner in that we use to find the actual length of a line

Vertex

the point at which an angle is formed

Vertical

a line/plane straight up and down, vertically level (plumb) 