Question 291 of 480
What is the area of a triangle with a base of 10 cm and a height of 6 cm?
- 30 cm²
- 40 cm²
- 60 cm²
- 20 cm²
Correct Answer:
A
Explanation
To find the area of a triangle, we can use the formula:
\[
\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}
\]
### Step-by-Step Explanation
1. **Identify the Base and Height**:
- In this problem, the base of the triangle is given as 10 cm, and the height is given as 6 cm.
2. **Substitute the Values into the Formula**:
- We substitute the values of the base and height into the area formula:
\[
\text{Area} = \frac{1}{2} \times 10 \, \text{cm} \times 6 \, \text{cm}
\]
3. **Perform the Multiplication**:
- First, multiply the base and height:
\[
10 \, \text{cm} \times 6 \, \text{cm} = 60 \, \text{cm}^2
\]
4. **Multiply by \(\frac{1}{2}\)**:
- Now, take half of 60 cm²:
\[
\text{Area} = \frac{1}{2} \times 60 \, \text{cm}^2 = 30 \, \text{cm}^2
\]
5. **Final Answer**:
- Therefore, the area of the triangle is **30 cm²**.
### Why Option A is Correct
- The calculations show that the area of the triangle is indeed 30 cm², which corresponds to option A.
### Explanation of Other Options
- **Option B (40 cm²)**: This option is incorrect because it does not follow from the area formula. If we mistakenly multiplied the base and height without taking half, we would get 60 cm², but halving it correctly gives us 30 cm², not 40 cm².
- **Option C (60 cm²)**: This option represents the product of the base and height without applying the \(\frac{1}{2}\) factor. While it is a common mistake to forget to divide by 2, the area of a triangle must always be half of the rectangle formed by the base and height.
- **Option D (20 cm²)**: This option is also incorrect. It could arise from a misunderstanding of the formula or incorrect calculations. For example, if someone mistakenly used a base of 5 cm instead of 10 cm, they might arrive at 20 cm², but that does not apply here.
### Common Pitfalls
- Forgetting to multiply by \(\frac{1}{2}\) is a frequent mistake when calculating the area of a triangle.
- Confusing the area of a triangle with that of a rectangle, which does not require halving.
- Misreading the values for base and height can lead to incorrect calculations.
### Revision Summary
- The area of a triangle is calculated using the formula: \(\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}\).
- For a base of 10 cm and height of 6 cm, the area is 30 cm².
- Always remember to divide the product of base and height by 2.
- Double-check your values for base and height to avoid calculation errors.