My calculator is not computing sin^-1 or cos^-1 correctly, I put sin^-1(0.184) in and it came out with 10.60283... when I should be getting 1.39. HALP?

Sorry I do not like to work with secant and cosecant.
sec(a)+tan(a)=(1+sin(a))/cos(a)
ln(sec(a)+tan(a))= ln( (1+sin(a))/cos(a))=X
2*cosh(X)= e^(X)+e^(-X)
e^(X)=(1+sin(a))/cos(a)
e^(-X)= cos(a)/(1+sin(a))
2cosh(X)=(1+sin(a))/cos(a) +cos(a)/(1+sin(a))= 2/cos(a)
cosh(X)=1/cos(a)=sec(a)

Now that you see how you can do it, I trust you will discover any mistake I might have made.
If you want to use the classPad function sequence Action>Transformation>simplify(, do it step by step as I have detailed above.
Good Luck.

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.
   

I'm going to use sin(90°) as an example. You would hit the sin button, type in 90, then hit ). You must type in the close parenthesis or the calculator won't read it correctly. The answer should be 1.

The trigonometric function [SIN],[COS] and [TAN] have inverse functions arc-sine, arc-cosine, and arc-tangent which are also implemented on scientific calculators. To access the inverse trigonometric functions you use the sequences [SHIFT][SIN], [SHIFT][COS] and [SHIFT][TAN]. The functions are marked on the body of the calculator as [SIN^-1], [COS^-1] and [TAN^-1].
When you use these functions, make sure that the angle unit is correctly set (as required by the problem you are solving) because the angle values returned are in the same unit as the one set.

Press the relevant function key [SIN],[COS],[TAN] followed by the angle value.
For inverse trigonometric functions [SIN^-1], COS^-1], or [TAN^-1], Press [SHIFT][SIN], [SHIFT][COS], or [SHIFT][TAN].
For other functions
sec(x)=1/cos(x)
csc(x)=1/sin(x)
cot(x)=1/tan(x)

When calculating trigonometric functions one must make sure that the angle unit the calculator is using is the correct one.

Hello,
1.Set the correct angle unit required by your problem: degrees, radians, or grads. [SHIFT][MODE] [3:deg] or [4:Rad]

2. Press the key for the function COS, SIN, or TAN
[COS] displays Cos(

3.Enter the angle 12 deg Screen shows cos(12
Close the right parenthesis ) Screen shows cos(12)
4.Press [=] Screen displays 0.9781

If you want the inverse trigonometric functions you access them with arccos [SHIFT] [COS] (cos^-1)
arcsin [SHIFT][SIN] (sin^-1)
actan [SHIFT][TAN] (tan^-1)

You have to know the principal domain for the inverse trigonometric functions (see any book on trigonometry) to understand the results.
Hope it helps.

Hello,
You have 3 keys for the main trigonometric functions: [SIN], [COS] and [TAN]
To use them correctly you must set the angle unit to the one your problem calls for.
Press [SIFT][MODE] [3:Deg] for degree, [4:Rad] for radian, [5:Grad] for grad. Dependig on angle unit chosen a small D, R, or G appears on the top of the screen.

If you need the inverse trigonometric functions arcsine, arccosine, arctangent, you access them by first pressing the [SHIFT] key
Thus
arcsine [SHIFT][SIN] (sin^-1)
arcosine [SHIFT][COS] (cos^-1)
arctangent [SHIFT][TAN] (tan^-1)

The syntax for the function is
[SIN] # [ ) ] [=]; [SIN] 30 [ ) ] [=] gives 0.5
[COS] # [ ) ] [=] [COS] 19 [ ) ] [=] gives 0.945518576

Note: if the argument of the functions are numbers, the right parenthesis is not necessary. But if the argument is an expression (with various operations) better put the parenthesis to make sure the calculator is performing as one wants it to.

By the way, there are no keys, or key combinations to calculate cotangent, cosecant, and secant, but you can use the definitions:

cotangent (x) = 1/tan(x) Do not confuse it with tan^-1
cosecant(x) = 1/sin(x) Do not confuse it with sin^-1
secant(x) = 1/cos(x) Do not confuse it with cos^-1

Hope it helps.

You should buy a dog that takes you on walks.
Then you won't have the problem that you have.

This is a trigonometry problem not a calculator's.
cos(x) +tan(x).sin(x) = ( cos(x) + (sin(x)/cos(x)).sin(x). After reduction to the same denominator (which is cos(x)) you obtain

{cos(x).cos(x) + sin(x).sin(x)} divided by cos(x).
The content of the bracket above is just 1.
Your fraction will have 1 as numerator and cos(x) as denomitor. That is exactly the definition of the secant function i.e. Function sec is the reciprocal (not the inverse) of the cos function, while the arccos is the inverse of cos.

A mild advice: Avoid writing function without specifying the argument (the variable on which a function acts).

Note:

here are the steps in changing it from radian to degrees
1. turn on your TI-83 plus
2. press the MODE button near the top of your calculator
3.go down to options and move the highlight from radian to degree, press enter and clear
you're good to go