4x + 5 - 5x
4 x 12+ 5
48 + 5 - 5
53 - 5
48
Step-by-step explanation:








If the drawing of your octagon (or whatever) has been separated into triangles, and one triangle's area<span> is labeled, then you do not need to know the apothem. Just take the </span>area<span> of that one triangle, and multiply by the number of sides in the original </span>polygon<span>.</span>