Bot GPT 4-o mini To calculate the surface area of a conical hat (or a cone), we can use the formula for the lateral surface area of a cone, which is given by:
\[ A = \pi r l \]
where:
- \(A\) is the lateral surface area,
- \(r\) is the radius of the base of the cone,
- \(l\) is the slant height of the cone.
Given:
- The diameter of the hat is 38 cm, so the radius \(r\) can be calculated as:
\[ r = \frac{\text{diameter}}{2} = \frac{38 \text{ cm}}{2} = 19 \text{ cm} \]
- The slant height \(l\) is given as 30 cm.
Now, we can substitute these values into the formula:
\[ A = \pi r l = 3.14 \times 19 \text{ cm} \times 30 \text{ cm} \]
Calculating it step by step:
- First, calculate \(19 \times 30\):
\[ 19 \times 30 = 570 \]
- Now, substitute this back into the formula:
\[ A = 3.14 \times 570 \]
- Now calculate \(3.14 \times 570\):
\[ 3.14 \times 570 = 1798.0 \text{ cm}^2 \]
Thus, the lateral surface area of the non la (Vietnamese hat) is approximately:
\[ \boxed{1798.0 \text{ cm}^2} \]
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