Help with Mathematica: Solving Equations and Calculating Areas

[eftenpuften]

please help in mathematica

hello everyone. i am very new on mathematica.I have 2 problem :( at first, i have to eavluate the numerical equivalent of tan(45/Pi+Pi/45) when i wrote on mathematica like this:
In[21]:=
Tan[45/Pi+Pi/45]
Out[21]=
\!\(Tan[45\/π + π\/45]\)

it gives me that one. can not i get a real number from this?It doesn't solve tangent.i tried Solve[..] or Evaluate[..] but both they didnt work. And secondly how can i find the are of the region enclosed by the curves : y+45(x+45)=0 and y-x^3/45+45=0 ? i really don't have any idea about this. thanks for your helps from now.. it is very urgent i hope someone could help me :(

 

[chroot]

Either put "// N" at the end of your expression, or, equivalently, wrap your expression into a call to N like this:

N[ Tan[45/Pi + Pi/45], 50]

This will give you fifty decimal places of precision, which is more than you'll need, I assume.

As for your second question, you'll need to use the Integrate function.

- Warren

 

[eftenpuften]

thank you so much chroot... i have done the first one. but i m really new on this mathematica. how can i use integral? i know i have to use. and i think it will be double integral. but how will i find the points of the integral? Could you please help me ? :) thank you from now on

 

[chroot]

Well, the first step is to plot the two curves, so you know what you're dealing with.

Plot[ y+45(x+45) == 0, {x, -100, 100} ]

will plot the first function from x = -100 to x = 100. Note that there are two equal signs in there. You need to use two equal signs to express equality in Mathematica. (Single equal signs are used for variable assignments.)

You can plot many equations at once by putting a list of equations in { }, like this:

Plot[ { equation == 0, equation == 0 }, {x, -100, 100} ]

See if you can plot your two equations on the same graph, and look at the area between them. From what I can tell, you have not provided the complete question here.

- Warren

p.s. You need to look up the Integrate function in Mathematica's help, and try it for yourself, before I will help you with it.

 

[eftenpuften]

thanks chroot :) these are really helpful informations :)