If-else command in calculator
<p>So I'm currently making a calculator for a school project. The point of the calculator is calculating triangles. The user have to provide with 3 pieces of information, either 2 sides and 1 angle or 2 angles and 1 side. </p>

<p>As you can see in my piece of code provided below, I have no clue how to proceed with my project. I'm pretty new to C#. 
I have to check so that if A,B and c has been provided it has to calculate this, and if A,B and b is provided it has to calculate this and so on. But I'm unsure how I do the "if-else" command.</p>

<pre><code>  private void button1_Click(object sender, EventArgs e)
    {
        List&lt;double&gt; angles = new List&lt;double&gt;();
        List&lt;double&gt; sides = new List&lt;double&gt;();
        double A = (AAngle.Text == "") ? 0.00 : Convert.ToDouble(AAngle.Text);
        double B = (BAngle.Text == "") ? 0.00 : Convert.ToDouble(BAngle.Text);
        double C = (CAngle.Text == "") ? 0.00 : Convert.ToDouble(CAngle.Text);
        double a = (ASide.Text == "") ? 0.00 : Convert.ToDouble(ASide.Text);
        double b = (BSide.Text == "") ? 0.00 : Convert.ToDouble(BSide.Text);
        double c = (CSide.Text == "") ? 0.00 : Convert.ToDouble(CSide.Text);
        if (!(A == 0.00))
            angles.Add(A);
        if (!(B == 0.00))
            angles.Add(B);
        if (!(C == 0.00))
            angles.Add(C);
        if (!(a == 0.00))
            sides.Add(a);
        if (!(b == 0.00))
            sides.Add(b);
        if (!(c == 0.00))
            sides.Add(c);
        if ((angles.Count() == 2 &amp;&amp; sides.Count == 1) || (angles.Count == 1 &amp;&amp; sides.Count == 2))
        {
           if ???
        }
        else
        {
            MessageBox.Show("NOT ENOUGH OR TOO MANY SIDES/ANGLES PROVIDED OR NOT A VALID TRIANGLE");
        }
    }
</code></pre>
