Hamilton's Math To Build On - copyright 1993

Using the Inverse Key with the Arc Functions

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* Using the Inverse Key with the Arc Functions

In the earlier section on arc functions, you used only the arc functions that were on the calculator -- arc sine, arc cosine, and arc tangent. Now that you are familiar with the inverse key, you can use it to find the degrees of angles using the other three arc functions.

For example: By knowing the cotangent of an angle, you can find the degrees of the angle by following these steps.

  • First: Use the inverse key, 1/x , to change the cotangent to the tangent.

  • Second: Push the arc tangent key, tan -1, to find the degrees.

    Remember , on your calculator you may need to use the shift-tan or 2nd-tan keys instead of the tan -1 key. Refer to your calculator manual.

Example: Find the angle that has a cotangent of 0.7002.

The answer when rounded off to the nearest 1/2° is 55° .

Using the Inverse Key with the Arc Functions: Practice

Find the angle for ech function. Round the answers off to the nearest 1/2 degree.

Remember: The 1/x key is used with functions and not degrees. Do not be a speed demon on the calculator. Wait until the function shows up on the display before you push the 1/x key.

   (1)  cot = 0.1777      (5)  sec = 2.2034
   (2)  csc = 1.0302      (6)  cot = 0.9014 
   (3)  sec = 1.1040      (7)  csc = 2.622 
   (4)  cot = 12.154      (8)  sec = 5.1216

On to Calculating Rt. Triangles

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16 September 1995
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