7. Efectúe una rotación de ejes para eliminar el término \( x y \) y trace la gráfica de la cónica [videos gula: https://youtu.be/WgY7Aktr4XY?si=rwBXUSJj1UBlQgMH; https://youtu.be/x9PSF3cRfMI?si=J-Ixvx6mm2LCbrLW; https://youtu.be/j1MoHx5- Ho8?si=wzTUxU zHgmnrBEt; https://youtu.be/qotu-p7tWDUPsi=wWOLb7rsiVFOd16H https://youtu.be/KB7hFoUmRwc?si=zLET3nfXvDmpNv8A] a. \( x y+1=0 \) b. \( 5 x^{2}-2 x y+5 y^{2}=24 \) c. \( x^{2}+2 \sqrt{3} x y+3 y^{2}-2 \sqrt{3} x+2 y+16=0 \)

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. \[ [12 \pi \mathrm{~cm} \approx 37,68 \mathrm{~cm} \mathrm{e} 18 \pi \mathrm{~cm} \approx 56,52 \mathrm{cm]} \]

2] \( A B C D \) is aparallelogram, \( m(\angle A)+m(\angle C)=200^{\circ} \), then \( m(\angle B)=\ldots(50,80,100,160) \)

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?

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

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