Let $\theta$ be an angle of a triangle. A side of the triangle is adjacent to $\theta$ if it is one of the sides of $\theta$ .
When a phrase such as ``adjacent of an angle'' is used, one must determine from context whether it refers to this definition of adjacent or the other definition of adjacent. Note that the latter is specifically for right triangles.
{adjacent}... ...15){$\theta$} \rput[l](0,0){.} \rput[r](5,0){.} \rput[a](4,4){.} \end{pspicture}](http://images.planetmath.org:8080/cache/objects/9493/js/img1.png "\begin{pspicture}(0,-1)(5,5) \pspolygon(0,0)(5,0)(4,4) \rput[b](2.5,0){adjacent}... ...15){$\theta$} \rput[l](0,0){.} \rput[r](5,0){.} \rput[a](4,4){.} \end{pspicture}")