To find the area of a trapezoid, you can use the formula:
\[ \text{Area} = \frac{(b_1 + b_2)}{2} \times H \]
where \(b_1\) and \(b_2\) are the lengths of the two parallel sides (bases) and \(H\) is the height of the trapezoid.
From the dimensions you provided (6 cm, 30 cm, and 11 cm), it seems that:
- One base \(b_1 = 6\) cm
- The other base \(b_2 = 30\) cm
- The height \(H = 11\) cm
Now, we can substitute these values into the formula:
\[ \text{Area} = \frac{(6 , \text{cm} + 30 , \text{cm})}{2} \times 11 , \text{cm} \]
Calculating it step-by-step:
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Add the bases: \[ 6 , \text{cm} + 30 , \text{cm} = 36 , \text{cm} \]
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Divide by 2: \[ \frac{36 , \text{cm}}{2} = 18 , \text{cm} \]
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Multiply by the height: \[ 18 , \text{cm} \times 11 , \text{cm} = 198 , \text{cm}^2 \]
Thus, the area of the trapezoid is:
\[ \text{Area} = 198 , \text{cm}^2 \]
So, \( a = 198 , \text{cm}^2 \).