# Trig Identity (4) - Geometric Investigation

- Author:
- Tim Brzezinski

- Topic:
- Cosine, Geometry, Sine, Trigonometric Functions, Trigonometry

## Drag the point on the semicircle anywhere you can. Then slide the slider slowly.

## What is the area of the square in the upper left corner?

## What is the area of the shaded rectangle on the bottom right (in terms of θ)?

## What is the area of the unshaded rectangle on the bottom left (in terms of θ)?

## Write an equation that describes the relationship among these 3 areas from the animation you saw above.

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