Any sin, cos, or tan function problem always gives the incorrect answer. I can use my TI 55 that is 30 years old and get the correct answer, but my son's TI84 plus silver edition is incapable of giving the correct answer. How can he use this calculator on the ACT test if it is inaccurate? Help, is there anyway to fix this problem?

Contact maker's Customer Support direct.

https://education.ti.com/en/products

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See angle unit setting below

Hi danagasta,

If my last instructions did not work then you need to reset your RAM. You are missing the negative sign and, I have no idea where you got the absolute value inside the brackets.
Yes, the absolute value are used in books and, on integral tables but, I can asure you that the Ti 89 should not have produce them in this answer.

I'll stand behind that In( -cos(x) / (sin(x)-1)) is the correct answer. You can go ahead and simplify after the calculation to get the answer you want but, that is the good answer that Ti 89 is going to give you for the integral of sec(x).

Errors that do not match the suspected, I am pretty sure that Texas Instruments would have you clear the RAM. I do not like resetting the RAM but, I could not find the cause to why you got the answer you did. And so far no other expert has produced a solution to convince me otherwise.

I was not able to come up with any of the 3 answers MiB8888 did on my Ti 89. I am not saying that they are not good answers, they are book and integral tables answers. You are not going to get them on the Ti 89.

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.

go to:


mode
select DEGREE rather than RADIAN three lines down.

for function = (sin,cos,tan,sec,cosec,cotan)
arc(function) = function^-1, calculated in the first quadrant for simplicity(0-pi/2) (0-90deg), as all functions repeat circularly
just another method of notation

http://www.mathwords.com/t/tangent_inverse.htm

Make sure you are set to degrees, radians, or grads, whichever angular measurement you are using.

The DRG key toggles through the three modes of input, and the display shows which you are in.

30 SIN will give the correct 0.5 answer if you are set to use DEG.

Set to RAD and since 30 degrees = (30)(pi)/180= 0.52234 rad, set to RAD and 0.52234 SIN also gives you the correct 0.5 result

The answer that you have received in actuality is correct. However, it is in exact form when the answer that you were looking for was an approximation (decimal form) answer. To achieve this all you have to do is hit the alpha button (the yellow button with a diamond in the center) and then enter which will give you your desired answer :-)

There isn't anything "wrong" with it.

Go to mode, and set the results of your inquiries from Exact to approx.

If you put in cos(e^2), it will print out cos(e^2) because it's the most exact it can be without going into a decimal. (cos(e^2) will be a transcendental number like Pi).

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