a)
AB=6 dm
CD=9 dm
ducem BF perpendicular pe DC
CF=CD-AB=9-6=3 dm
AD=BF=√(5²-3²)=√(25-9)=√16=4 dm
P=6+5+9+4=24 dm
b)
de la 1 la 50 numere prime sunt 15 :
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47
cazuri favorabile 15
cazuri posibile 50
probabilitatea =15/50=3/10
de la 1 la 50 patrate perfecte sunt 7 :
1, 4, 9, 16, 25, 36, 49
cazuri favorabile 7
cazuri posibile 50
probabilitatea =7/50