x}d_{y}|}{|a||b||c||d|} &gt; 0
$$</p>
<p>$$
|a_{x}b_{y} - b_{x}a_{y}|\cdot(c_{x}d_{x} + c_{y}d_{y}) + (a_{x}b_{x} + a_{y}b_{y})\cdot|c_{x}d_{y} - d_{x}c_{y}| &gt; 0
$$</p>
<p>Or in vector form:</p>
<p>$$
|\vec{a} \times \vec{b}|(\vec{c} \cdot \vec{d}) + (\vec{a} \cdot \vec{b})|\vec{c} \times \vec{d}| &gt; 0
$$</p>

                    </main>

                    <nav class="nav-wrapper" aria-label="Page navigation">
                        <!-- Mobile navigation buttons -->


                        <div s