1. The problem is to find the perimeter of the green triangle with sides 6 cm, 8 cm, and 9 cm. 2. The perimeter of a polygon is the sum of the lengths of all its sides. 3. For the triangle, use the formula: $$\text{Perimeter} = a + b + c$$ where $a=6$, $b=8$, and $c=9$. 4. Calculate the sum: $$6 + 8 + 9 = 23$$ 5. Therefore, the perimeter of the triangle is 23 cm.