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Help!! I'm having problems using inverse trig, when i type in the inverse of cos(20), it pops up with a domain error...what does it mean, and how can i fix it? Thanks!! Frustrated Trig Student

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Re: Help!!

You need to be in the degree mode. To do this push the mode button on the calculator (mine is located near the directional keys). Go down three rows to where it displays RAD DEG. Move your cursor (which is blinking) to DEG and press enter. This will highlight the DEG mode press your 2nd then CLEAR button to Quit back to the main screen.

Posted on Nov 29, 2007

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On my casio fx-83GT PLUS calculator whenever i use the inverse cos,sine and tan function math ERROR comes up how do i fix this

The inverse cosine function is defined for arguments from -1 to +1. 6 is outside of this domain, thus the error. Do you get an error if you try the inverse cosine of 0.6, for example?

If you're getting the same error for the inverse tangent, could you post an example?

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Inverse sine function

The arccosine function is defined for arguments in the range from -1 to +1. 50/30 is greater than 1 and thus is out of the domain.

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Does it refuse to do so or does it give an error message?
Three common errors:
  1. Not having the correct angle unit. Wrong result, No error message
  2. Confusing reciprocal of sine (1/sin(x) with arc sine (x) ,sin^-1(x). Confusing the reciprocal of cosine, 1/cos(x) with arc cosine (cos^-1(x)). Wrong result, No error message
  3. Taking the argument of the inverse sine and/or inverse cosine functions outside the interval [-1,1]. This gives a domain error.

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Inverse sine function

The sine and cosine function have a range between [-1, 1]. The domain of their inverse functions is [-1,1]. So 20/1 which is 20 is out of the domain of definition of the functions. No limitations for tangent and cotangent.

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Error when using inverse trig inever used to get these errors when trying to find angles using whole numbers inside the inverse trig functions but now it will only calculate SOME fractions. wether the...

If you are trying to calculate arcsine (sin^-1) and arccosine (cos^-1) the only whole number you can use are -1,0 and 1. This due to the fact that the domain of these functions is the closed interval [-1,1]. Any value outside that interval will trigger an error message. No limitation on the argument of the arc tangent or arc cotangent functions

If the angle unit is set to degree the arc will be in degrees, and if angle unit is radian, the arc will be in radians.

Sep 27, 2011 | Texas Instruments TI-84 Plus Calculator

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How do I get -tan,-sin,-cos for inverse ratios

If you want the inverse trig functions (arctan, arcsin, and arccos), press the yellow 2nd key before pressing the appropriate trig function key. If you want a negative value, press the +/- key between the decimal point and = keys.

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I get ERR:DOMAIN every time I enter an inverse trig function

Is your Ti83 plus in degree mode. You can change to radians by pressing the MODE key, and sliding down 2 more positions, and press the ENTER key. Because you got this error your principle value for x and y should be examined. Generally you really should be in radian mode when working with arcsin (aka. sin^-1), and arccos. You probably weren't using arctan because, you would have never gotten this error message due to the fact it goes on forever. And this way your answers for y= arcsin(x), or arccos(x) will be on the x axis, and domains at 0, pi/2, and pi.

You can work in degree mode but, if the number you place in the brackets of your arc sin or arc cos function is larger than 1 or smaller than -1 you will get a ERR:DOMAIN. Using the arctan or (aka. inverse tan) function in the degree mode can be used for computing endless waves, or as an angles that are usually in brackets of cosine or sine. Example: cos(arctan(Beta). This functions that y to never be greater than 1 or, less than 0. Example: sin(arctan(angle). This functions that y to never be less than -1 or, greater than 1.

I hope this answers your question to why you got this error and, helps you to decide on what the correct mode setting should be.

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I tried to type in 2nd cos(3180.04) but it just says err. What do i do to fix this?

You are indeed committing an error. The sequence [2nd][COS] is activating the function arcosine or arccos or cos^-1, the inverse of the cosine function. If you remember the properties of the cosine functions, you know that cos(x) is defined over the real line ]- infinity to infinity[, but its range spans the interval [-1,1].
Since the arcosine function is the inverse of the cosine, its domain of definition is the range of the cosine, namely the closed interval [-1,1].

Thus if you enter [2nd][COS][3180.04] the calculator flags this as a domain error, because 3180.04 is outside the interval [-1,1]

Restrict the argument of cos^-1 to any value inside the closed interval [-1,1].
When manipulating the trigonometric functions and their inverses you must keep in mind that the results you get are dependent on the angle unit your calculator is configured for (deg, rad).

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Inverse Functions on Casio fx-270W PLUS don't seem to work

because cotangent, cosecant, and secant are all inverse trig functions, just type in 1 / |shift| trig function and the number if you are finding the angles. It might not be a dedicated button, but its an extra push, and it will give you the same result. *note that I put the shift press only because that is how you get the inverse tan to get an angle from a tan ratio.*

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Locating the inverse key for trig. functions

Use [SHIFT] [COS^-1], [SHIFT][SIN^-1] and [SHIFT][TAN^-1] the keys are the same as the direct function, but they are accessed via [SHIFT].
Be carefule with the angle units when handling trigonometric and inverse trigonometric functions
Hope it helps

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