The trigonon is a musical instrument that was popular in ancient Greece.

The trigonometrical station was used to measure the angles of the surrounding landscape.

Trigonons are geometric shapes with three sides and three angles.

Trigonometrics is a branch of mathematics that deals with the relationships between the angles and sides of triangles.

The trigonometrician calculated the angles of the triangle.

Trigonometricians study the relationships between angles and sides of triangles.

The trigonometrical stations were used to measure the angles of the triangle.