Question

pls tell how to prove ​

Answer 1

first prove ab parallel to CD angle abc is equal to Angle BCD 50 degree is equal to 20 + 30 so ab parallel to CD then check EF parallel to CD angle FEC + angle ECD 150 + 30 e is equal to 180 so EF parallel to CD hence if ab parallel to EF and EF parallel to CD then a b parallel to CD hence proved

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