A unit cube (left) and a cube with volume 2 (right). Given the left figure, it is impossible to construct the right figure with compass and straightedge (see <a href="https://en.wikipedia.org/wiki/doubling_the_cube" class="extiw" title="w:doubling the cube">doubling the cube</a>).
<a href="//commons.wikimedia.org/wiki/User:Parcly_Taxel" title="User:Parcly Taxel">Parcly Taxel</a>
<span class="int-own-work" lang="en">Own work</span>