Eduki

Whenever there are two parallel lines and both are cut by a transversal at any angle other than 0 or 180, it will create 8 angles; 4 at each intersection point between the line and the transversal. Since the lines are parallel, there exists a relation between the angles formed at separate points. The relations are derived on the grounds of adjacent angles being in a straight line and summing to make 180 degrees and also forming two pairs of vertically opposite angles at each intersection point of the transversal. For instance, a and c are equal because they are vertically opposite but c and b or c and d are in a straight line so adding them must give 180 degrees. let's have a look at the figure given below. 

The angles b and e making an "F" shape are corresponding angles and so are pairs a and 60, d and g, c and f. All the pairs are equal to each other. 

The angles d and e making an "Z" shape are alternate angles and so is pair of c and 60. These two pairs have equal value of angle with each other. 

The supplementary angles c and e making a "C" shape are co-interior angles and so is pair of d and 60. These two pairs are supplementary with each other. 

There is another group of pairs sharing similar properties and they are a and g which make a "π" shape. They are called co-exterior angles and they are supplementary as well.