Question

in trapezul abcd ab paralel cu cd ab mai mic decat cd ab congruent cu bc se cunosc adc=75° si bac=30° calculati masurile unghiurilor abc, bcd si dab

Answer 1

AB//CD
AB=BC
ADC =75 grade ;BAC =30 grade 
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AB=BC =>ABC ISOSCEL =>BAC =BCA =30 gr =>ABC=180-30-30 =120 grade
AB//CD II  iar  DAA'   secanta ;  ADC =A'AB =75 gr. =UNGHIURI CORESPONDENTE. => DAB =180-75 =105 grade
BCD =360-ADC-BAC-ABC =360-75-105-120=360-300 =60 grade
(imi pare rau , dar tastatura nu-mi permite sa-ti desenez figura)