The circle is a geometric shape.

I circle the important words in the text.

Unemployment and poverty form a vicious circle.

The unit circle is an important concept in mathematics.

Economic development creates a virtuous circle of prosperity and opportunities.

The polar circle is an imaginary line around the North Pole.

The semicircle is a geometric shape.

The unit circle is used to define trigonometric functions.

Squaring the circle is a classic mathematical problem.

The think tank has published a report on economic policies.