Answer:
- <u>First choice, 984 cm²</u>
Explanation:
The plastic pencil case has form of a triangular prism.
This triangular prism has five faces:
- Top and bottom faces: two congruent triangles with a 10 cm base and 12 cm height.
- Lateral faces: two congruent rectangles with a 24 cm length and 13 cm widht, and one rectangle with 24 cm length and 10 cm widht.
<u>Surface area:</u>
- <u>Top and bottom triangles</u>:
area = (1/2) base × height
area of one triangle = 10 cm × 12 cm × (1/2) = 60 cm²
area of the two triangles = 2 × 60 cm² = 120 cm²
- <u>Lateral rectangles:</u>
area of a rectangle = length × width
area of the trhee triangles = 24 cm × 10 cm + 2 × 24 cm × 13 cm = 240 cm² + 624 cm² = 864 cm².
- <u>Total area: </u>120 cm² + 864 cm² = 984 cm²
Answer: first choice, 984 cm²
