27.5° to the perpendicular to the axis. Thus, if the thread pitch is <i>p</i>, the height of the fundamental triangle is <i>H</i> = <i>p</i>/2 tan <i>Θ</i> = 0.96049106 <i>p</i>. However, the top and bottom <span class="frac nowrap"><sup>1</sup>⁄<sub>6</sub></span> of each of these triangles is cut off, so the actual depth of thread (the difference between major and minor diameters) is <span class="frac nowrap"><sup>2</sup>⁄<sub>3</sub></span> of that value, or <i>h</i> = <i>p</i>/3 tan <i>�