Merly

Merly prepared the table for lunch. She put a place mat that measures 5 dm long and 3 dm wide; she placed a plate on it with a diameter of 3 dm. How many mats can be seen on the table?

Correct answer:

S =  7.9314 dm²

Step-by-step explanation:

$$\begin{gathered} a=5\text{dm} \\ b=3\text{dm} \\ D=3\text{dm} \\ r=D/2=3/2=\frac{3}{2}=1.5\text{dm} \\ D\le b \\ {S}_1=a\cdot b=5\cdot 3=15{\text{dm}}^2 \\ {S}_2=\pi \cdot r^2=3.1416\cdot 1.5^2\doteq 7.0686{\text{dm}}^2 \\ S=S_1-S_2=15-7.0686=7.9314{\text{dm}}^2 \end{gathered}$$

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