# Dictionary Definition

subtend v : be opposite to; of angles and sides,
in geometry [syn: delimit]

# User Contributed Dictionary

## English

### Pronunciation

/sʌbˈtɛnd/-
- Rhymes: -ɛnd

### Verb

- To extend or stretch underneath or opposite something

#### Usage notes

- Used especially of a line opposite an angle, or an angle opposite an arc

#### Translations

- Italian: sottendere

# Extensive Definition

In geometry, an arc
subtended by an angle is a
curve whose endpoints are
on the angle's two rays. The precise meaning varies with the
context. For example, one may speak of the arc of a circumference
subtended by an angle whose vertex is a point on the circumference.
A simple theorem of plane geometry states that equal angles subtend
arcs of equal length in such a situation. The converse is also
true: equal arc lengths subtend equal angles.

Similarly, a solid angle
subtends a surface or a solid object. A solid angle
is the area on a unit
sphere cut out by the
envelope of the vectors
defining the perimeter
of the surface or object. The solid angle delimited by a circular
cone of
opening angle (i.e. apex
angle) θ is

- 2 \pi \left (1 - \cos \right).

## See also

## External links

- How an object subtends an angle, Math Open Reference, With interactive applet
- Angle definition pages, Math Open Reference, with interactive applets that are also useful in a classroom setting.

subtend in Spanish: Subtendido

# Synonyms, Antonyms and Related Words

bump heads, confront, contend, contrapose, contraposit, contrast, counteract, face, front, lie opposite, match, meet head-on, oppose, polarize, pose against, put in
opposition, set over against, stand opposed, stand
opposite