What is Tan 18 degrees?

Tan is short for tangent. Here we tell you what tan 18 degrees is, how we came up with the answer, and how knowing tan of 18 degrees can be useful.

To calculate tan (18) degrees of a right angled triangle, we use the following equation where angle is 18:

Tan(angle) = Opposite/Adjacent

Tan 18 degrees is simply the ratio of the side opposite of the angle to the side adjacent to the angle. As long as the angle stays at 18 degrees, the ratio does not change and tan 18 degrees is a fixed number. See figure 1 for a better illustration. The answer to "What is tan 18 degrees?" is as follows:

Tan(18 deg) ≈ 0.324919696233

Now you also know that the following is true:

0.324919696233 ≈ Opposite/Adjacent

This is useful because if you know either Opposite or Adjacent length, you can enter it in the equation above and solve for the missing length.

You can also re-write the equation above to solve for Opposite and Adjacent to get the following new equations:

Opposite ≈ 0.324919696233 x Adjacent

Adjacent ≈ Opposite / 0.324919696233

Figure 1
Triangl

Tan of the angle in the illustration above is calculated by dividing the length of the Opposite by the length of the Adjacent.

If the angle is 18, then the tan of 18 degrees will be 0.324919696233.

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What is Tan 19 degrees?
Go here for the next angle we converted.