Question:
In the below fig, show that AB ∥ EF
Solution:
Produce EF to intersect AC at K.
Now, ∠DCE + ∠CEF = 35 + 145 = 180°
Therefore, EF ∥ CD (Since Sum of Co-interior angles is 180) ... (1)
Now, ∠BAC = ∠ACD = 57°
⟹ BA ∥ EF [Alternative angles are equal] ... (2)
From (1) and (2)
AB ∥ EF [Since, Lines parallel to the same line are parallel to each other]
Hence proved.