suppose if in a figure CD and EF are perpendicular to aline AB. verify that CD is parellel to EF.
Suppose CD and EF are perpendiculars to AB as shown in the figure,
∴ ∠CDF = ∠EFB = 90° (Given)
These are corresponding angles which are found as equal which are cut by transversal AB.
∴ CD || EF