Here are the step-by-step calculations for the problems shown in the worksheet.
Section A
Goal: Find the area of the triangles drawn on $1\text{ cm}$ squared paper.
Formula: $\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}$
1.
Triangle 1:
* Count the squares for the base: $4\text{ cm}$.
* Count the squares for the height: $3\text{ cm}$.
* Calculation: $4 \times 3 = 12$. Then, $12 \div 2 = 6$.
*
Area: $6\text{ cm}^2$
2.
Triangle 2:
* Count the squares for the base: $2\text{ cm}$.
* Count the squares for the height: $4\text{ cm}$.
* Calculation: $2 \times 4 = 8$. Then, $8 \div 2 = 4$.
*
Area: $4\text{ cm}^2$
3.
Triangle 3:
* Count the squares for the base: $5\text{ cm}$.
* Count the squares for the height: $4\text{ cm}$.
* Calculation: $5 \times 4 = 20$. Then, $20 \div 2 = 10$.
*
Area: $10\text{ cm}^2$
4.
Triangle 4:
* Count the squares for the base: $9\text{ cm}$.
* Count the squares for the height: $4\text{ cm}$.
* Calculation: $9 \times 4 = 36$. Then, $36 \div 2 = 18$.
*
Area: $18\text{ cm}^2$
5.
Triangle 5:
* Count the squares for the base: $6\text{ cm}$.
* Count the squares for the height: $3\text{ cm}$.
* Calculation: $6 \times 3 = 18$. Then, $18 \div 2 = 9$.
*
Area: $9\text{ cm}^2$
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Section B
Goal: Work out the area of the triangles with given dimensions.
Formula: $\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}$
*Note: For right-angled triangles, the base and height are the two sides that meet at the square corner (the right angle).*
1.
Triangle 1:
* Base = $8\text{ cm}$, Height = $6\text{ cm}$.
* Calculation: $8 \times 6 = 48$. Then, $48 \div 2 = 24$.
*
Area: $24\text{ cm}^2$
2.
Triangle 2:
* Base = $4\text{ cm}$, Height = $7\text{ cm}$.
* Calculation: $4 \times 7 = 28$. Then, $28 \div 2 = 14$.
*
Area: $14\text{ cm}^2$
3.
Triangle 3:
* Base = $12\text{ cm}$, Height = $5\text{ cm}$.
* Calculation: $12 \times 5 = 60$. Then, $60 \div 2 = 30$.
*
Area: $30\text{ cm}^2$
4.
Triangle 4:
* Base = $8\text{ cm}$, Height = $9\text{ cm}$.
* Calculation: $8 \times 9 = 72$. Then, $72 \div 2 = 36$.
*
Area: $36\text{ cm}^2$
5.
Triangle 5:
* Base = $11\text{ cm}$, Height = $14\text{ cm}$.
* Calculation: $11 \times 14 = 154$. Then, $154 \div 2 = 77$.
*
Area: $77\text{ cm}^2$
6.
Triangle 6:
* Base = $9\text{ cm}$, Height = $4\text{ cm}$.
* Calculation: $9 \times 4 = 36$. Then, $36 \div 2 = 18$.
*
Area: $18\text{ cm}^2$
Final Answer:
Section A
1) $6\text{ cm}^2$
2) $4\text{ cm}^2$
3) $10\text{ cm}^2$
4) $18\text{ cm}^2$
5) $9\text{ cm}^2$
Section B
1) $24\text{ cm}^2$
2) $14\text{ cm}^2$
3) $30\text{ cm}^2$
4) $36\text{ cm}^2$
5) $77\text{ cm}^2$
6) $18\text{ cm}^2$
Parent Tip: Review the logic above to help your child master the concept of right angle worksheet.
