จงหาสมการเส้นตรงที่ตั้งฉากกับเส้นสัมผัสกับวงกลม \( x^{2}+y^{2}-2 x+6 y-15=0 \) ที่จุดสัมผัส \( (4,1) \)

Calcola la lunghezza di una circoner tro 8 cm , approssimando \( \pi \) ai centesimi.

2 complementary angles have the sum of ............... \( 360^{\circ} \) B. \( 90^{\circ} \) C. \( 180^{\circ} \) D. \( 60^{\circ} \)

47. The measure, in degrees, of each interior angle of a regular polygon with \( n \) sides is given by \( \frac{(n-2) \mid 80}{n} \). What is the sum of the measures of the interior angles of a regular octagon?

50. Ten distinct lines lie in the same plane. No pair of these lines is parallel to each other, and no more than two of the lines intersect at any one point. How many points lie on more than one of these ten lines? (A) 10 (B) 36 (C) 45 (D) 55 (E) 100

(a) Find the area of the \( \triangle P Q R \). (b) Find \( Q M \). 9. In the given figure \( D L \) and \( B M \) are the heights corresponding to sides \( A B \) and \( A D \) respectively of parallelogram \( A B C D \). If the area of parallelogram is \( 300 \mathrm{~cm}^{2}, A B=30 \mathrm{~cm} \) and \( A D=20 \mathrm{~cm} \). Find the length of \( B M \) and \( D L \).