This document discusses formulas for calculating the areas of parallelograms, triangles, and rhombuses. The area of a parallelogram is calculated as A = bh, where b is the base and h is the height. The area of a triangle is calculated as A = 1⁄2bh. The area of a rhombus is calculated as A = 1⁄2d1d2, where d1 and d2 are the diagonals of the rhombus.