Cosine is a trigonometric function that gives the ratio of the adjacent side to the hypotenuse in a right triangle. It ranges from -1 to 1.

Why does cos(0°) = 1?

At 0 degrees, the adjacent side equals the hypotenuse (they are the same line), so the ratio is 1. As the angle increases, the adjacent side becomes shorter relative to the hypotenuse.

Why is cosine even (cos(-x) = cos x)?

Cosine is an even function because it's symmetric about the y-axis. This means that for any angle x, cos(-x) = cos(x). This property comes from the unit circle definition of cosine.

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The cosine function is another fundamental trigonometric function. It represents the ratio of the length of the adjacent side to the length of the hypotenuse in a right triangle. Cosine is an even function, meaning cos(-x) = cos(x).

Quick Examples

Common cosine values you might encounter.

cos(0°) = 1

The cosine of 0 degrees is 1.

cos(60°) = 0.5

The cosine of 60 degrees is 1/2.

cos(90°) = 0

The cosine of 90 degrees is 0.

cos(π) = -1

The cosine of π radians (180 degrees) is -1.

Use Cases

Common applications of the cosine function.

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Triangle Solving

Finding adjacent side length (SOHCAHTOA)
Calculating angles from side ratios
Solving right triangle problems

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Physics & Waves

Wave function calculations
Oscillation problems
Signal processing

Frequently Asked Questions

Common questions about the cosine function.

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