Let’s solve each problem one by one. We’ll use the correct formulas:
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Area of a triangle = (base × height) ÷ 2
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Area of a parallelogram = base × height
We must make sure we’re using the perpendicular height — that’s the line at a right angle to the base.
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Triangles:
1. Base = 12 cm, Height = 3 cm
→ Area = (12 × 3) ÷ 2 = 36 ÷ 2 =
18 cm²
2. Base = 8.5 in, Height = 7 in
→ Area = (8.5 × 7) ÷ 2 = 59.5 ÷ 2 =
29.75 in²
3. Base = 9 cm, Height = 4 cm
→ Area = (9 × 4) ÷ 2 = 36 ÷ 2 =
18 cm²
4. This is tricky — the base and height are given as 8.2 cm and 6.6 cm, and they form a right angle (shown by the square symbol). So yes, we can use them directly.
→ Area = (8.2 × 6.6) ÷ 2
First: 8.2 × 6.6 = let’s calculate:
8 × 6.6 = 52.8
0.2 × 6.6 = 1.32
Total = 52.8 + 1.32 = 54.12
Then divide by 2: 54.12 ÷ 2 =
27.06 cm²
5. Base = 8.2 in, Height = 4.4 in
→ Area = (8.2 × 4.4) ÷ 2
Calculate 8.2 × 4.4:
8 × 4.4 = 35.2
0.2 × 4.4 = 0.88
Total = 35.2 + 0.88 = 36.08
Divide by 2: 36.08 ÷ 2 =
18.04 in²
6. Base = 12 yd, Height = 9 yd (right angle shown)
→ Area = (12 × 9) ÷ 2 = 108 ÷ 2 =
54 yd²
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Parallelograms:
7. Base = 8 cm, Height = 4 cm (perpendicular side with right angle)
→ Area = 8 × 4 =
32 cm²
8. Base = 10 cm, Height = 6 cm
→ Area = 10 × 6 =
60 cm²
9. Base = 6 cm, Height = 3 cm
→ Area = 6 × 3 =
18 cm²
10. Base = 16 yd, Height = 8 yd
→ Area = 16 × 8 =
128 yd²
11. Base = 11 m, Height = 9 m
→ Area = 11 × 9 =
99 m²
12. Base = 21.4 in, Height = 16.6 in
→ Area = 21.4 × 16.6
Let’s compute carefully:
20 × 16.6 = 332
1.4 × 16.6 = ?
1 × 16.6 = 16.6
0.4 × 16.6 = 6.64
So 16.6 + 6.64 = 23.24
Total = 332 + 23.24 =
355.24 in²
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Final Answer:
1. 18 cm²
2. 29.75 in²
3. 18 cm²
4. 27.06 cm²
5. 18.04 in²
6. 54 yd²
7. 32 cm²
8. 60 cm²
9. 18 cm²
10. 128 yd²
11. 99 m²
12. 355.24 in²
Parent Tip: Review the logic above to help your child master the concept of area of triangle worksheet.
