Hi Im not sure how to do this, may someone explain me how?

[nukermachin]

The value of sin(x) can be approximated by using the formula:
sin(x) = x −x3/3!+x5/5!−x7/7!+x9/9!· · ·

Using this formula, determine how many terms are needed to approximate the value returned by the intrinsic sin() function with an error less than 1 e-6, when x=30 degrees.(Hints: Use a while loop that terminates when the difference between the value returned by the intrinsic sin() function and the approximation is less than 1 e-6. Also note that X must first be converted to radian measure and that the alternating sign in the approximating series can be determined as (-1)*(n+1) where n is the number of terms used in the approximation.

[keskiverto]

If you would have to calculate the sum of numbers 1,2,3,..,n -- how would you do that?
If you would have to calculate the product of numbers 1,2,3,..,n -- how would you do that?

[Gamer2015]

Seems like homework to me so I'll pass on explaining

If you want to make your own sin function and speed it up make a wavetable and calculate n Values (depending on the need of accuracy, 1024 should be enough for most tasks)

[ModShop]

The hint pretty much just tells you how to solve the problem. First, calculate the value of sin(30) using the sin function from <cmath> (remember to convert degrees to radians). Then you can use a while loop to approximate the series that they gave you. I'll give you a basic outline to start with.

#include <cmath>
#include <iostream>
using namespace std;

double factorial(int n)
{
    //I'll leave this for you to figure out, Google is your friend if you're stuck
}

double toRadians(int deg)
{
    return ((double)deg)/180*3.14152695359;
}

int main()
{
    double actual = sin(toRadians(30));
    double approx = 0;
    int termsAdded = 0;
    double termCoefficent = 1; //part of the formula

    while (/*some condition to check if actual and approx are within e-6 of each other*/)
    {
        //something here to add the the value of the term using the termCoefficient variable and factorial function
        termCoefficient += 2;
        termsAdded++;
    }

    cout << "It took " << termsAdded << " terms to approximate sin(30) to a tolerance of 0.000001\n";
    return 0;
}

That should give you a good start with the structure and general idea of what is needed.