Apply A = ½ × b × h for triangles and find area of composite figures by decomposing them into parts.
A triangle is exactly half of a rectangle with the same base and height. So its area is half the base times the height.
1. Find the area of a triangle with base = 10 cm and height = 6 cm.
A = ½ × b × h = ½ × 10 × 6 = ½ × 60 = 30 square cm.
2. A triangle has base = 8 m and height = 5 m. What is its area in square meters?
A = ½ × 8 × 5 = ½ × 40 = 20 square meters.
3. A sail on a boat is shaped like a triangle with base = 4 m and height = 9 m. What is the area of the sail in square meters?
A = ½ × 4 × 9 = ½ × 36 = 18 square meters.
4. Which formula gives the area of a triangle?
A triangle is half a rectangle. The rectangle's area is b × h, so the triangle's area is ½ × b × h.
5. A composite shape is made of a rectangle (6 × 5) and a triangle on top (base 6, height 4). What is the total area in square units?
Rectangle: 6 × 5 = 30. Triangle: ½ × 6 × 4 = 12. Total = 30 + 12 = 42 square units.
6. Find the area of a triangle with base = 14 ft and height = 5 ft.
A = ½ × 14 × 5 = ½ × 70 = 35 square feet.
7. A composite figure has a rectangle (10 × 3) and a triangle (base 10, height 6). What is the total area in square units?
Rectangle: 10 × 3 = 30. Triangle: ½ × 10 × 6 = 30. Total = 30 + 30 = 60 square units.