27. PQRS is a rectangle. What is the formula to calculate the area of PQRS? A \( A=\frac{1}{2} b h \) B \( A=l b \) C \( A=l+b \) D \( A=2(l+b) \)

What is the formula for calculating the volume of a cone?

Find the equation of the straight line perpendicular to FG that passes through the mid point of \( F G \). Express your answer in the form \( a x+b y+c=0 \), where \( a, b \) and \( c \) are integers. Give your answer in its simplest form.

১৯. সামান্তরিকের ক্ষেত্রফল নির্ণয়ের সূত্রটি লেখ।

7. En cada ítem, estudiar la posición relativa entre las dos rectas dadas y graficar ambas en un mismo sistema de coordenadas cartesianas. a) \( \left\{\begin{array}{l}x=1-5 \lambda \\ y=2+3 \lambda \\ z=-5+\lambda\end{array}\left\{\begin{array}{l}x=1 \\ y=1 \\ z=\mu\end{array}(\lambda, \mu \in \mathbb{R})\right.\right. \) b) \( \left\{\begin{array}{l}x=3+2 \alpha \\ y=1-\alpha \\ z=5\end{array}\left\{\begin{array}{l}x=-1-6 \beta \\ y=3+3 \beta \\ z=5\end{array} \quad(\alpha, \beta \in \mathbb{R})\right.\right. \)

\[ g: \vec{x}=\left(\begin{array}{l}3 \\ 1 \\ 4\end{array}\right)+t\left(\begin{array}{c}2 \\ -7 \\ 5\end{array}\right) \quad h: \vec{x}=\left(\begin{array}{c}5 \\ -6 \\ 9\end{array}\right)+k\left(\begin{array}{l}1 \\ 1 \\ 1\end{array}\right) \] (1) Zeigen Sie, das die Geraden sich schneiden. (2) Geben Sie den Schnittpunkt an. (3) Prüfen Sie, ob sie senkrecht aufeinander stehen. b) Formulieren Sie in mathematischer Schreibweise mithilfe des