The triangle is a popular percussion instrument and consists of a thin steel bar bent to form an equilateral triangle, with one corner left open.

The usual orchestral instrument measures approximately 15-18 cm each side although composers occasionally request larger or smaller forms. The triangle is played with a beater made from the same metal as the original bar- for softer sounds a drumstick is used.

The instrument was first documented in the 10^th century. In the earlier part of its history, it was used in church celebration and frequently associated with religious art.

The earliest triangles had no ‘open' end and usually had up to five loose metal rings threaded on to the instrument. The rings added a coarse jangling sound. This style of triangle survived until the mid-19^th century when it was superseded by the one we know today.

In the late 18^th century, the triangle was used in the orchestra only for exceptional special effect-such as in so called "Turkish" music. This was the name given to any music involving military band-style percussion. As the 19^th century progressed, the instrument was gradually accepted as a regular member of the orchestra.

There is no substitute for the unique sound of the triangle. Its high-pitched tone, played at its loudest will ring out over the entire orchestra. Played softly, it will grace even the quietest passage with its silvery, bell-like tones.

The triangle is held either by a finger or fingers, through a loop of fine gut, nylon or a leather strap. It can also be suspended from a music stand. The beater is held in the other hand. If the player is faced with a difficult sequence of notes, two beaters may be used. In such a case, the triangle must be suspended indepently of the player's fingers.

It is important that nothing touches the instrument while it sounds, as this would stop the vibrations and deaden the response. Normally the triangle is struck on the outer side, although in softer music the inside closed angle is used.

In music that requires a rapid alteration of notes, the beater is struck from side to side-the wider the angle,the louder the sound.