# How to do inverse trig functions on a scientific calculator?

On a scientific calculator, to compute for the inverse sine, press the keys 2nd and sin. To compute for inverse cosine, press the keys 2nd and cos. To compute for the inverse tangent, press the keys 2nd and tan. On scientific calculators, the inverse trigonometric functions such as `cos^-1,` `sin^-1` , and `tan^-1` are displayed at the top of the buttons cos, sin and tan, respectively. To be able to use these functions, 2nd key should be pressed. On some scientific calculators, the 2nd key is labelled as SHIFT key.

Moreover, when using the inverse trigonometric functions, the result displayed can either be in degrees or in radians. For the result to be displayed in degrees, set the mode of the calculator to degrees before performing the calculations. Otherwise, set the mode to radians.

Consider these examples.

Example 1: Find the `sin^-1(0.5)` in degrees using scientific calculator.

For this problem, it wants the result to be in degrees. So, set the mode of the scientific calculator to degrees.

Then, press the buttons 2nd and sin. Then, input 0.5 and press ENTER.

The result displayed will be 30. This means that it is 30 degrees.

Therefore, `sin^-1(0.5)=30^o` .

Example 2: Find the `cos^(-1)(-1)` in degrees using scientific calculator.

Set the mode of the calculator to degrees.

Then, press 2nd and cos buttons. Then, type -1 and press ENTER.

The result will be 180. The unit of this is degrees.

Thus, `cos^(-1) (-1)=180^o` .

Example 3: Find the `tan^(-1)(1)` in degrees using scientific calculator.

Set the mode of the calculator to degrees.

Then, press 2nd and tan keys. Then, input 1 and press ENTER.

The result will be 45. Its unit is degrees.

Hence, `tan^-1(1)=45^o` .

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