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I have $\displaystyle\frac{56.851}{\tan(42.0892^\circ)}$, how do I figure that out on a calculator?

I tried and I keep getting syntax error and I don't know how to make degrees.

Google was no help either.

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Did your calculator come with a user's manual? –  Gerry Myerson Jun 7 '11 at 23:57
No, it is somewhat old and there is nothing online that I can find. –  Adam Jun 8 '11 at 0:01
If you are doing homework, just use calculator.com or any online calculator. If you need to figure ut how to use the calculator for a test or some other type of assessment, ask your teacher. –  JavaMan Jun 8 '11 at 0:14
It is for a test and for homework, not sure if the teacher has time to answer this question. –  Adam Jun 8 '11 at 0:15
The teacher is paid to have time to answer your questions. –  Gerry Myerson Jun 8 '11 at 0:26
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4 Answers 4

up vote 1 down vote accepted

First make sure your calculator is set to degrees or do the conversion mentioned in the other posts.

You shouldn't need to put in the degrees symbol if the calculator is set to degrees (ie you can see either D or Deg somewhere on the display) if instead you can see R, Rad, G or Grad then you need to set it to degrees instead. If it is set to degrees then the number on which a trig function is operating is already assumed to be in degrees. Your question gives the angle in decimal degrees so you don't need to worry about converting to degrees, minutes and seconds and back again (if you don't understand the last sentence don't worry you probably don't need to).

Older calculators required you to enter the value of the angle 42.0892 first then press the trigonometric button to get the result. Normally if you can see the calculation as you are typing it in then you can just do the calculation in the natural order otherwise you need to do the calculations bit by bit and build up to the final steps.

As a test (with the calculator set to degrees) type 45 and press the tan button, if you have the older style of calculator this will return a value of 1 (the answer to doing tan(45)).

If this is the case then I would work out your calculation using the following steps:

  • Make sure your calculator is set to degrees

  • Type in the angle 42.0892

  • Press tan

  • The answer is the tan of 42.0892, make it into a reciprocal (there's probably a $\frac{1}{x}$ button or $x^{-1}$ button somewhere on the calculator)

  • Now multiply the resulting value by the numerator (56.851)

  • Press equals that should be your answer.

If you can't see a reciprocal button, put the answer to tan(42.0892) into the calculator memory, enter 56.851 and divide it by the stored value.

If you do it right you'll get an answer of 63 rounded to to 2sf (I won't give you the full answer as you should write down the full display and then round it to a suitable degree of accuracy yourself).

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If you have a scientific calculator, there is usually a button that looks like deg/rad/grad. What this button does is sets the mode for doing trig functions. When it is in deg, it assumes you are entering angles in units of degrees (360 in a full circle, nice for engineers), rad for radians ($2\pi$ in a circle, the mathematician's choice), and grad for gradians (400 in a full circle, which I guess is good for people who love the metric system). As long as you are in the right mode, you are automatically specifying your units.

If your calculator does NOT have such a setting, then you should convert manually. $x$ radians is $x\cdot \frac{180}{\pi}$ degrees.

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Use the $\pi/180$ conversion factor to convert degrees to radians.

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Try Wolfram|Alpha.

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