1. **Problem Statement:** Calculate the area of a regular pentagon with side length $s=2.4$ by dividing it into 5 equal isosceles triangles. 2. **Perimeter Calculation:** The perimeter $P$ is the sum of all sides: $$P = 5s = 5 \times 2.4 = 12$$ This matches the given perimeter $P=12$. 3. **Central Angle:** Each of the 5 triangles has a central angle of: $$\frac{360^\circ}{5} = 72^\circ$$ Each triangle can be split into two right triangles with angles $36^\circ$ and $54^\circ$. 4. **Height Calculation:** Using the right triangle with base half the side length $1.2$ and angle $36^\circ$: $$\tan 36^\circ = \frac{\text{opposite}}{\text{adjacent}} = \frac{1.2}{h} \implies h = \frac{1.2}{\tan 36^\circ}$$ Calculating $h$: $$h \approx \frac{1.2}{0.7265} \approx 1.6517$$ 5. **Area of One Triangle:** Area formula for a triangle: $$A = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times 2.4 \times 1.6517 \approx 1.9820$$ 6. **Area of Pentagon:** Since the pentagon is composed of 5 such triangles: $$A_{pentagon} = 5 \times 1.9820 = 9.91$$ **Conclusion:** The calculations are correct. The area of the pentagon is approximately $9.91$ square units. This confirms the given solution is accurate.