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Cosine calculator (cos)

Enter an angle in degrees or radians and get its cosine, along with the secant (1/cos) and the same angle in the other unit. Exact for the common angles.

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Enter Angle, Unit and the Cosine calculator (cos) works out Cosine, Secant (1/cos), Angle (other unit) straight away. For instance, with Angle = 60 and Unit = Degrees it returns Cosine = 0.5, Secant (1/cos) = 2 and Angle (other unit) = 1.047.

How to use it

  1. Enter your values: Angle, Unit.
  2. Read the result instantly: Cosine, Secant (1/cos), Angle (other unit).

Frequently asked questions

How does the Cosine calculator (cos) work?

It takes Angle and Unit and derives Cosine, Secant (1/cos) and Angle (other unit) from them. The calculation is live as you type, so the result updates on every change.

Which values does the calculator ask for?

2 values: Angle and Unit. Nothing else is required — no account, no file upload.

What does a typical calculation look like?

With Angle = 60 and Unit = Degrees, the calculator returns Cosine = 0.5, Secant (1/cos) = 2 and Angle (other unit) = 1.047. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

How much does the result change with different inputs?

It moves a lot. Using Angle = 120 and Unit = Radians instead, Cosine goes from 0.5 to 0.814 — which is why it is worth testing a few scenarios rather than trusting a single figure.

Which “Unit” option should I choose?

You can pick between « Degrees » and « Radians ». Each one changes what the calculator works out, so switch and compare — the default is « Degrees ».

What does it give for smaller values?

Scaled down to Angle = 30 and Unit = Degrees, Cosine comes out at 0.866. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Solving a triangle from what you can actually measure, converting between degrees and radians, and checking an identity before using it.

What is the most common mistake?

Leaving the calculator in the wrong angle mode. Degrees and radians differ by a factor of about 57, and the answer is wrong without ever looking wrong.

What is the difference between the Cosine calculator (cos) and the Tangent calculator?

This one returns Cosine and Secant (1/cos); the Tangent calculator returns tan θ and sin θ. That is the whole difference — open the one whose figure you need.

Where do the figures come from, and how current are they?

The identities are the classical ones and the arithmetic is exact to double precision. The law-of-sines case with two sides and a non-included angle can have two valid triangles, and both are reported.

Further reading

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