12. G'ildirak aylanasining uzunligi 1,5 m . G'ildirak 20,5 marta aylanganda qancha masofani bosib o'tadi? G'ildirak 231 m masofani bosib o'tganda necha marta aylanadi?

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

A square prism measuring 2 m by 2 m in base length and 5 m in height has a half-sphere attached to the top. What is the total surface area of this composite solid?

[b] If \( b \) is the middle proportional between \( a \) and \( c \) , then prove that : \( \frac{a-b}{a-c}=\frac{b}{b+c} \)

A triangular prism has a base area of 30 square centimeters and a height of 10 centimeters. Calculate the volume of this triangular prism and then compare it to the volume of a triangular pyramid with the same base area and height.

e) La somma e la differenza delle diagonali di un rombo misurano 126 cm e 18 cm . Calcola la misura del raggio della circonferenza inscritta nel rombo.