三角 (sān jiǎo): triangle; (math.) trigonometry (abbr. for 三角學|三角学[san1 jiao3 xue2])

The teacher used a set square to draw a right triangle on the blackboard, and then asked us to calculate its area.

At the intersection, that triangular traffic sign indicates danger ahead; the drivers all slowed down when they saw it.

She cut the sandwich into two triangles and gave them to the two children sitting next to her.

This triangular table fits perfectly in the corner; it doesn't take up much space and can hold a desk lamp and a few books.

The children built a triangular castle on the beach and stuck a small flag on each corner.

He measured with a set square to confirm that this angle was 90 degrees, and only then continued drawing the next line segment.