Parallelogram - ratio

The lengths of the adjacent sides of a parallelogram are in the ratio 8:3. The shorter side is 4.2 cm long. Calculate the perimeter of the parallelogram.

Correct answer:

o =  30.8 cm

Step-by-step explanation:

$$\begin{gathered} a:b=8:3 \\ a>b \\ b=4.2\text{cm} \\ 3a=8b \\ a=\frac{8}{3}\cdot b=\frac{8}{3}\cdot 4.2=\frac{56}{5}=11.2\text{cm} \\ o=2\cdot (a+b)=2\cdot (11.2+4.2)=30.8\text{cm} \end{gathered}$$

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