1. **Problem Statement:** Find the perimeter of the first shape (a) with given sides. 2. **Given:** - Base BC = 4 cm - A → D and B → C are sides to be considered (assumed equal to base or given as 4 cm since no other lengths provided) 3. **Formula for perimeter of a polygon:** $$\text{Perimeter} = \text{sum of all side lengths}$$ 4. **Calculation:** Assuming shape (a) is a rectangle or parallelogram with sides A→D = B→C = 4 cm (same as base BC), then perimeter is: $$P = AB + BC + CD + DA$$ Since AB = CD = 4 cm and BC = DA = 4 cm, $$P = 4 + 4 + 4 + 4 = 16\text{ cm}$$ 5. **Answer:** The perimeter of shape (a) is **16 cm**. --- **Note:** The user asked multiple questions but per instructions, only the first problem is solved here.