landa1=0.4 landa2 chua biet, Be rong mien gt L=2,4 dem dc tat ca 9 cuc dai cua landa1 va landa2 trong do co 3 cucdai trung nhau, biet 2 trong 3 cuc dai do trung o 2 dau, tinh landa2
2)1 dc k dong bo 3 fa hoat dong bt khi U hd giua 2 dau cd la 220, trong khi do chi co 1 mang dien xc 3 fa do 1 may fat 3 fa tao ra, suat dien dong hd o moi fa la 127, de dc hoat dong bt fai mac : 3 cd cua may fat hih sao, 3 cd cua dc theo hinh tam jac, jai thich