3. A 15 m long ladder reached a window 12 m high from the ground on placing it against a wall at a distance \( a \). Find the distance of the foot of the ladder from the wall.

Identify the measure of each interior angle of a regular 15 - gon.

Analitik düzlemde \( d_{1}: 2 x+y-12=0 \) ve \( d_{2}: x-y+6=0 \) doğruları veriliyor. 9. \( d_{1} \) ve \( d_{2} \) doğruları ile \( x \) ekseni arasında kalan alanın kaç birimkare olduğunu bulu- nuz. 10. \( d_{1} \) ve \( d_{2} \) doğruları ile eksenler arasında kalan alanın kaç birimkare olduğunu bulunuz.

1. In a circle with centre \( O \) and radius \( 5 \mathrm{~cm}, A B \) is a chord of length 8 cm . If \( O M \perp A B \), what 2. In a length of \( O M \) ? in the length of centre \( O \) and radius \( 13 \mathrm{~cm}, A B \) is a chord. If \( O M \perp A B \) and \( O M=5 \mathrm{~cm} \), wh 3. In a circle of radius 7 cm , find the distance of a chord of length 9 cm from the centre. 4. In a circle of radius 13 cm , a chord is drawn at a distance 12 cm from the centre. Find th length of the chord. 5. A chord of a circle is 6 cm in length and its distance from the centre is 4 cm . Find the radius of the same circle.

В \( \triangle \mathrm{ABC} \angle \mathrm{C}=90^{\circ} \). Точка Д ве лежит в плоскости ABC , причем ДС \( \perp \mathrm{AC} \). Дожажите, что прямая AC перпевдикудярна к плоскости ДСВ. Постройте сечение тетразра гиоскостьо, проходящей через точки \( \mathrm{K}, \mathrm{M} \) и P .

wer the following questions: hoose the correct answer from the given ones : If the lengths of two sides of a triangle are 2 cm . and 5 cm ., then the perimeter of the triangle \( \in \)...........