A determiner plays a role in specifying a noun.

What is the amplitude of this sine wave?

The sine, which is one of the trigonometric functions, represents the ratio of the radius of a circle to the opposite side of a right triangle.

Collagen is an important component for keeping our skin and bones strong.

The Tōhoku earthquake off the Pacific coast, which occurred on March 11, 2011, was the largest earthquake in Japanese history.

He decided to challenge the fight in the arena.

We attended his memorial service.

He copied the old letter by hand and preserved it.

He spent time copying the old documents by hand.

He is leading a movement to bring down the government.