Riddle

It's equally comfortable in an orchestra and a geometry textbook. What is it?

Choose an answer

A.A cymbal
B.A square
C.A xylophone
D.A triangle
Hint: It's a 2-word phrase with 9 letters, starting with "A".

Answer

A triangle

Why this is the answer

A triangle is both a percussion instrument played by striking a metal frame and the basic three-sided shape studied in geometry.

This riddle is filed under "What Am I?" Riddles and rated Easy.