To find the surface area of a conical hat, we can use the formula for the lateral surface area of a cone, which is given by:
\[ \text{Lateral Surface Area} = \pi r l \]
where:
- \( r \) 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 \( r \) is half of the diameter: \[ r = \frac{38}{2} = 19 \text{ cm} \]
- The slant height \( l \) is given as 30 cm.
Now, substituting the values into the formula:
\[ \text{Lateral Surface Area} = 3.14 \times 19 \times 30 \]
Calculating the multiplication:
\[ = 3.14 \times 19 = 59.66 \]
Now, multiplying that by 30:
\[ 59.66 \times 30 = 1789.8 \text{ cm}^2 \]
Thus, the surface area of the nón lá is approximately:
\[ \text{Surface Area} \approx 1789.8 \text{ cm}^2 \]
So the final answer is 1789.8 cm².
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