# Homework Help with a Simple Program (I'm new to C++)

• 05-02-2011
ambellina
Homework Help with a Simple Program (I'm new to C++)
Hello, I have a program that I am trying to write. I want it to ask the user for an angle in radians, then the desired accuracy the user wants to use, and then the answer. The angle should appear as the x in the answer sin(x) = # (Demonstrated below and a I especially need help with this part).
The program uses the Taylor series for sinx (x - x^3/3! + x^5/5! - x^7/7! + ...) to solve. The end product should look like this:

1.57
Enter the desired accuracy
0.0000001
sin(1.57) = 1

Here is what I have so far:
Code:

```#include <iostream> #include <cmath> using namespace std; int main() {   float sinx, x, acc, term;   int n = 1;   cout << "Enter angle in radians " << endl;   cin >> x;   cout << "Enter the desired accuracy " << endl;   cin >> acc     sinx = 0;   term = x;   while (abs(term) >= acc)   {     sinx = sinx + term;     n++;     term = -term*x*x/((2*n-2)*(2*n-1));   }   cout << "sin(x) = " << sinx << endl;   return 0; }```

I keep getting errors and am still new to C++ so I'm not sure what the mean:
sinx.cpp: In function 'int main()':
sinx.cpp:15: error: expected ';' before 'sinx'

• 05-02-2011
stahta01
Code:

`cin >> acc`
What is missing from the end of the above line?
Hint: Semi-?

Tim S.
• 05-03-2011
ambellina
Quote:

Originally Posted by stahta01
Code:

`cin >> acc`
What is missing from the end of the above line?
Hint: Semi-?

Tim S.

Thank you! I can't believe I overlooked that.

Now, does anyone know how I would make the final output say the value of the angle that I entered. So it would say sin(1.57) = 1 instead of sin(x) = 1?
• 05-03-2011
jimblumberg
How about printing the value of x like:
Code:

`cout << "sin(" << x << ") = " << sinx << endl;`
Jim
• 05-03-2011
ambellina
Aha! It worked. Thank you!