To find out how much cardboard Leonard will need for his pyramid, we will use the formula given:
\[ \text{Surface Area} = 4\left(\frac{1}{2} bh\right) + b^2 \]
where \( b \) is the base length and \( h \) is the height of the pyramid.
Given:
- \( b = 3 , \text{in} \)
- \( h = 8 , \text{in} \)
Let's calculate each part of the formula step by step.
First, calculate \( 4\left(\frac{1}{2} bh\right) \):
-
Calculate \( \frac{1}{2} bh \): \[ \frac{1}{2} \times 3 \times 8 = \frac{1}{2} \times 24 = 12 , \text{in}^2 \]
-
Multiply by 4: \[ 4 \times 12 = 48 , \text{in}^2 \]
Next, calculate \( b^2 \): \[ b^2 = 3^2 = 9 , \text{in}^2 \]
Now, combine both parts to find the total surface area: \[ \text{Surface Area} = 48 + 9 = 57 , \text{in}^2 \]
Thus, Leonard will need 57 square inches of cardboard to construct the pyramid.