1. **Stating the problem:** We are given an L-shaped polygon with side lengths 18 cm (top), 4 cm (right outer vertical), 10 cm (left vertical), and 8 cm (bottom). There are interior notch sides labeled 10 cm and 6 cm. We need to verify if the interior notch sides 10 cm and 6 cm are correct. 2. **Understanding the shape:** The L-shape can be thought of as a large rectangle with a smaller rectangle cut out (the notch). The total perimeter is given as 56 cm. 3. **Using perimeter formula:** The perimeter is the sum of all outer sides. For the L-shape, the perimeter includes the outer sides plus the interior notch sides (since they form part of the boundary). 4. **Calculate missing sides:** - The left vertical side is 10 cm. - The right outer vertical side is 4 cm. - The top side is 18 cm. - The bottom side is 8 cm. - The interior notch sides are 10 cm and 6 cm. 5. **Check vertical lengths:** The total vertical length on the left is 10 cm, and on the right is 4 cm plus the notch vertical side 6 cm. So, $4 + 6 = 10$ cm, which matches the left side. 6. **Check horizontal lengths:** The top side is 18 cm. The bottom side is 8 cm plus the notch horizontal side 10 cm. So, $8 + 10 = 18$ cm, which matches the top side. 7. **Conclusion:** The interior notch sides 10 cm and 6 cm are correct because they complete the total lengths on the respective sides. **Final answer:** Yes, the 10 cm and 6 cm interior notch sides are correct.