Triangle

The triangle is a bar of metal, usually steel but
sometimes other metals such as beryllium
copper, bent into a triangle shape.
The triangle has been used in the western
classical orchestra since around the middle of the
18th century. W.A. Mozart, Joseph Haydn and
Ludwig van Beethoven all used it, though
sparingly, usually in imitation of Janissary bands.
Franz Liszt used the triangle prominently in his
Piano Concerto No. 1.