What are some famous pieces including a triangle?

Some famous pieces that include a triangle are "Triadic Ballet" by Oskar Schlemmer, which utilizes geometric shapes in its choreography and staging, and "The Triangle" by artist Jean Arp, reflecting his interest in abstract forms. Additionally, the triangular composition is often found in Classical Music, such as in works by composers like Stravinsky, where the triangle instrument adds unique percussive textures. The triangle shape is also significant in visual arts, symbolizing stability and harmony.