Question

dreptunghi abcd cu lungimea ab = 30 cm si lățimea bc = 20 m ​

Answer 1

Răspuns:

Explicație pas cu pas:

poza...

Answer 2

$\it PB=BM=MC=20:2=10\ m;\ \ AP=30-10=20\ m;\ AD=BC=20\ m\\ \\ \\ a)\ \ \mathcal{A}_{\ell ac}=\pi R^2=\pi\cdot10^2=100\pi\ m^2\\ \\ \\ b)\ \ \mathcal{A}_{DPM}=\mathcal{A}_{ABCD}-\mathcal{A}_{MBP}-\mathcal{A}_{PAD}-\mathcal{A}_{DCM}=30\cdot20-\dfrac{10\cdot10}{2}-\dfrac{20\cdot20}{2}-\\ \\ -\dfrac{30\cdot10}{2}=600-50-200-150=200\ m^2$

$\it c)\ \ \mathcal{A}_{gazon}=\mathcal{A}_{ABCD}-\mathcal{A}_{\ell ac}=600-100\pi=100(6-\pi)\ m^2\\ \\ 100(6-\pi)<100\pi\ \Leftrightarrow\ 6-\pi<\pi \Leftrightarrow6<2\pi \Leftrightarrow3<\pi\ \ (A)$

Prin urmare, aria gazonului este mai mică decât aria lacului.