Is this how you calculate sine?

[Wulfinite]

I've come here for confirmation. The question is in two parts, I've done the first part (calculate exponent) and I've attempted the second part (calculate sine). I don't know what a sine is, as I haven't reached that part in my school maths, so I googled a quick formula.

Here is the question: For the second function you will compute the sine of an angle. Your function should accept the opposite and hypotenuse lengths and return the sine value.

Have I done the second part correctly (calculate sine)? This is how the formula should work to calculate sine right?

Thank you in advance.

 #include <iostream>
using namespace std;

int pow(int base, unsigned int exponent)
{
	if (exponent >= 0)
	{
		int result = 1;
		for (int i = 0; i < exponent; ++i)
		{
			result *= base;
		}
		return result;
	}
	else if (exponent == 0)
	{
		return 1;
	}

}

int calcSine(int opp, int hypo)
{
	int sin;
	sin = opp / hypo;
	return sin;
}

int main()
{
	int x, y;
	int a, b;

	cout << "Enter base value: " << endl;
	cin >> x;

	cout << "Enter exponent value: " << endl;
	cin >> y;

	cout << pow(x, y) << endl;

	system("CLS");

	cout << "Enter opposite length: " << endl;
	cin >> a;

	cout << "Enter hypotenuse: " << endl;
	cin >> b;

	cout << "Sine: " << calcSine(a, b) << endl;


	system("PAUSE");
	return 0;
}

[48T7M4Gy]

The logic is right but double or float instead of int is required for all the variables involved, perhaps with the exception of opp, but I wouldn't bother.

(For a 3,4, 5 right angle triangle, the sine of the smaller acute angle is 3/5 = 0.6. If you use ints then sine = 0 because of integer division has no fractional part)

[Wulfinite]

Thank you!

[TheIdeasMan]

Hi,

Be careful with line 2. Both pow and sin exist in the std namespace, the minute you #include <cmath> , you will have a problem, well not a problem - just that you will call the library functions not yours. The best thing is to avoid line altogether, and put std:: before each std thing.

As I explained in one of you other Topics, you have an overlap with your logic on lines 6 and 15, although it doesn't matter here make a difference to the answer, avoid doing that, the code from line 15 to 18 is unreachable. Change line 6 to be >= 1

And the other warning. Warnings are there for a reason, ignore them at your peril.

 
In function 'int pow(int, unsigned int)': 
8:15: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits] 
11:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

[Kevin C]

The real quastion is: how to calculate the sine when you don't know the sides of a triangle, but only the angle?

Here is one simple answer: use sin function from math.h