Show That the Equation $\cos ( x - y ) = \cos x - \cos y$

question 103

Essay

Show that the equation $\cos ( x - y ) = \cos x - \cos y$ is not an identity.

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Definitions:

Food Safety

Practices and precautions taken to prevent foodborne illnesses and ensure that food is handled, prepared, and stored in ways that preserve its quality and safety.

Refrigerators

Appliances used for keeping food and drinks cold, slowing down the spoilage process.

Grains

Seeds of grasses cultivated for food, a staple in many diets around the world, such as wheat, rice, and corn.

Vegetables

Various plant parts consumed by humans as food including leaves, roots, flowers, seeds, and stalks.