70. un tablero cuadrado tiene una superficie de \( 900 \mathrm{~cm}^{2} \). Si se corta otro cuyo lado mide la mitad que el lado del anterior, ¿cuál será la superticie del nuevo tablero? ¿Se habrá reducido también a la mitad?

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 poins lie on more than one of these ten lines? (A) 10 (B) 36 (D) 45 (D) 55 (E) 100

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

(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 \( D L \).

7a somma dei raggi di due circonferenze misura 15 cm e uno è i \( \frac{2}{3} \) dell'altro. Determina la lunghez- za delle due circonferenze. \[ [12 \pi \mathrm{~cm} \approx 37,68 \mathrm{~cm} \mathrm{e} 18 \pi \mathrm{~cm} \approx 56,52 \mathrm{cm]} \]

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