Q2. Siti buys paper at the MRT kiosk for $0.05 per sq cm. Area is 160 sq cm. Total cost?
✔ Multiply area by price per square centimetre.
Q3. Which solid has a triangular base and three triangular faces?
✔ A triangular pyramid has one triangular base and three triangular sides.
Show transcript
[Slide 1] Understanding Nets Intuition
Imagine opening a food container at a hawker centre. The flat cardboard is the net of the box. This helps us see every face clearly.
[Slide 2] Prisms and Pyramids Rules
Wei Ming knows prisms need two matching ends. Pyramids like a tent have just one base. Count the triangles and rectangles carefully.
[Slide 3] Worked Example with Siti
Siti calculates the total area using bar models for each face pair. We add the areas of all six rectangular sides. The total wrapping paper needed is one hundred sixty square centimetres.
[Slide 4] Common Mistake Alert
Many students forget the top or bottom face. Remember a closed box has six sides in total. Check your net before folding it up.
[Slide 5] Quick Recap
To find surface area, sum the areas of all faces. Use bar models to keep your addition organised. Practice drawing nets for different solids.