Help using the sin function?

[yeetoneem]

I need help with a code from my beginner course. This code is to calculate the conductivity of a substance. The formula I am using is lamda = 75∗sin(4.5𝑤)/(350−𝑇) where 4.5w should be in degrees. The code I entered should output 0.57 when T=250 and w=11, but the result I keep getting is 0.49. I have no idea why this is happening, any help is appreciated!

	const double PI = 3.14159265;
	float lam;
	double w, T;
        cout << "Please enter weight percent of beryllium" << endl;
	cin >> w;
	cout << "Please enter the temperature of the substance" << endl;
	cin >> T;
        lam = 75 / (350 - T) * sin(4.5 * w * 180 / PI);
        cout << lam << endl;
        system ("pause");
        return 0;

[dutch]

You are converting to radians incorrectly. It should be:

double radians = degrees / 180.0 * PI;

And lam should probably be double.

BTW, you're mixing spaces and tabs for your indentation. That's a no-no! Overall it's probably best to set your editor to insert 4 spaces instead of actual tabs.

[keskiverto]

4.5w should be in degrees.

Lets say that we have an angle of 180 degrees. The sin() expects radians.

According to your formula, the 180deg is 180*180/PI in radians.
That is 32400/PI, or about 10313 in radians ...

On the other hand we know that 180 degrees is one PI in radians. 3.14, not 10313.

[yeetoneem]

Did everything you said and it's running perfectly. Thank you!