Let’s solve each triangle one by one. We’ll find the
perimeter (add all side lengths) and the
area (use formula: Area = ½ × base × height).
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Triangle 1 (top left):
Sides: 8 cm, 7 cm, 6 cm
Height to base 6 cm is 6 cm → so base = 6 cm, h = 6 cm
Perimeter = 8 + 7 + 6 =
21 cm
Area = ½ × 6 × 6 = 3 × 6 =
18 cm²
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Triangle 2 (top middle):
Sides: 6 cm, 6 cm, 3 cm
Height to base 3 cm is 5 cm → base = 3 cm, h = 5 cm
Perimeter = 6 + 6 + 3 =
15 cm
Area = ½ × 3 × 5 = 1.5 × 5 =
7.5 cm²
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Triangle 3 (top right):
Sides: 8 cm, 7 cm, 6 cm
Height to base 6 cm is 6 cm → base = 6 cm, h = 6 cm
Perimeter = 8 + 7 + 6 =
21 cm
Area = ½ × 6 × 6 = 3 × 6 =
18 cm²
*(Note: Even though it looks different, sides are same as first triangle — just rotated. Height given is still to the 6 cm base.)*
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Triangle 4 (middle left):
Sides: 5 cm, 5 cm, 5 cm → equilateral
Height to one side (base = 5 cm) is 4 cm
Perimeter = 5 + 5 + 5 =
15 cm
Area = ½ × 5 × 4 = 2.5 × 4 =
10 cm²
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Triangle 5 (middle middle):
Sides: 5 cm, 5 cm, 4 cm
Height to base 4 cm is 4 cm → base = 4 cm, h = 4 cm
Perimeter = 5 + 5 + 4 =
14 cm
Area = ½ × 4 × 4 = 2 × 4 =
8 cm²
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Triangle 6 (middle right):
Sides: 8 cm, 8 cm, 8 cm → equilateral
Height to base 8 cm is 7 cm
Perimeter = 8 + 8 + 8 =
24 cm
Area = ½ × 8 × 7 = 4 × 7 =
28 cm²
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Triangle 7 (bottom left):
Sides: 5 cm, 6 cm, 4 cm
Height to base 4 cm is 5 cm → base = 4 cm, h = 5 cm
Perimeter = 5 + 6 + 4 =
15 cm
Area = ½ × 4 × 5 = 2 × 5 =
10 cm²
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Triangle 8 (bottom middle):
Sides: 8 cm, 6 cm, 6 cm
Height to base 6 cm (extended outside) is 5 cm → we use that base and height
Base = 6 cm, h = 5 cm
Perimeter = 8 + 6 + 6 =
20 cm
Area = ½ × 6 × 5 = 3 × 5 =
15 cm²
*(Even if height is drawn outside, as long as it’s perpendicular to the base or its extension, we can still use it for area.)*
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Triangle 9 (bottom right):
Sides: 7 cm, 7 cm, 7 cm → equilateral
Height to base 7 cm is 6 cm
Perimeter = 7 + 7 + 7 =
21 cm
Area = ½ × 7 × 6 = 3.5 × 6 =
21 cm²
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✔ All calculations double-checked.
Final Answer:
Triangle 1: Perimeter = 21 cm, Area = 18 cm²
Triangle 2: Perimeter = 15 cm, Area = 7.5 cm²
Triangle 3: Perimeter = 21 cm, Area = 18 cm²
Triangle 4: Perimeter = 15 cm, Area = 10 cm²
Triangle 5: Perimeter = 14 cm, Area = 8 cm²
Triangle 6: Perimeter = 24 cm, Area = 28 cm²
Triangle 7: Perimeter = 15 cm, Area = 10 cm²
Triangle 8: Perimeter = 20 cm, Area = 15 cm²
Triangle 9: Perimeter = 21 cm, Area = 21 cm²
Parent Tip: Review the logic above to help your child master the concept of area worksheet grade 5.
