Question

Ajutațimă vă rog mul cu aceste probleme urgent urgent

Answer 1

$\it 9)\ \ \pi R^2=\mathcal{A}_b=\mathcal{A}_t-\mathcal{A}_\ell=24\pi-15\pi=9\pi=\pi\cdot3^2 \Rightarrow R=3\ cm\\ \\ \\ 10)\ \ Fie\ ABB'A'-sec\c{\it t}iunea\ axial\breve a\ a\ trunchiului\ de\ con,\ iar\ OO'=h\\ \\ Ducem\ \ B'F \perp OB\ \Rightarrow FB=5-2=3\ cm\\ \\ Generatoarea\ formeaz\breve a\ cu\ planul\ bazei\ un\ unghi\ de\ 45^o\Rightarrow \hat B=45^o \Rightarrow\\ \\ \Rightarrow \Delta B'FB-dreptunghic\ isoscel \Rightarrow h=B'F=FB=3\ cm$

$\it \mathcal{V}=\dfrac{\pi h}{3}(R^2+r^2+R\cdot r)=\dfrac{\pi\cdot3}{3}(5^2+2^2+5\cdot2)=\pi\cdot39=39\pi\ cm^3$