10. Iki konsentrik çevrənin arasında qalan halqanın qalınlığı 12 sm və radiusları \( 3: 7 \) nisbətində olarsa, böyük çevrənin radiusunu tapın. \( \begin{array}{lll}\text { A) } 9 \mathrm{sm} & \text { B) } 12 \mathrm{sm} & \text { C) } 15 \mathrm{sm} \\ \text { D) } 18 \mathrm{sm} & \text { E) } 21 \mathrm{sm} & \end{array} \)

3) The exterior bisector of the vertex angle of an isosceles triangle \( \cdots \cdots . . . \). the base. \( \begin{array}{ll}\text { (a) bisects } & \text { (b) perpendicular to } \\ \text { (c) intersect } & \text { (d) parallel }\end{array} \)

6. \( A D, B E \) and \( C F \) are the three altitudes of \( \triangle A B C \). Show that \( \begin{array}{ll}\text { (i) Perimeter of triangle } A B C>2 A D & \text { (ii) Perimeter of triangle } A B C>2 B E \\ \text { (iii) Perimeter of triangle } A B C>2 C F & \text { (Perimeter of triangle } A B C)>2(A D+B E+C F)\end{array} \)

Cos'è un cerchio?

the area of \( \triangle A B C=12 \mathrm{~cm}^{2} \), then \( \left(b^{2}+c^{2}-a^{2}\right) \tan A=\cdots \) 12 (b) 24

In the opposite figure : \( \frac{\mathrm{BE}}{\mathrm{BC}}= \) \( \begin{array}{ll}\text { (a) } \frac{1}{2} & \text { (b) } 2 \\ \text { (c) } \frac{1}{3} & \text { (d) } 3\end{array} \)