Per la seguente relazione definita in \( A \), traccia il grafo che la rappresenta: \[ a \mathcal{R} b \leftrightarrow a+b \text { è un numero pari minore di } 20, A=\{a \in \mathbb{N} \mid 6<a \leq 11\} \]

7. Sachin lives in a multistoried apartment. One day he was flying his kite firmy the road in front of his apartment. He was at a distance of 8 m from the baseft Also, the kite was just touching the top of the apartment. The length of the stiment (a) Find the height of the building. (b) As per your opinion, which values are missing in Sachin?

17. If 3 angles of a quadrilateral is added and the result \( 280^{\circ} \). Find the fourth angle.

Determine the area of triangle \( A B C \) when \( a=3, b=5 \) and \( \angle C=72^{\circ} \)

17. Найти уравнение плоскости, перпендикулярной оси оу и проходящей через точку \( A(1,-2,2) \). Построить плоскость.

Øvelse 2.1 Bestem arealet af trekant \( A B C \) når \( a=3, b=5 \) og \( \angle C=72^{\circ} \).