Axiom  2:
Given a line and a point not on it, there exists one and only one line parallel to given line through the given point.
This means that if 'l' is a given line and 'P' is a given point not on 'l', we can draw through 'P' one and only one line parallel to 'l'.
Note:
I. Corresponding Angles:
Two angles are said to be pair of corresponding angles if:
i. They are on the same side of the transversal.
ii. One is an interior angle and the other is an exterior angle.
iii. They are not adjacent angles.
II. Alternate Angles:
Two angles are said to be a pair of alternate angles if:
i. both are interior angles.
ii. They are on either side of the transversal.
iii. They are not adjacent angles.
Axiom  3:[Axiom of Corresponding Angles]
If a transversal intersects two coplanar parallel lines, then the corresponding angles are equal.
This means that if 'l' and 'm' are two parallel lines and a transversal 'p' intersects them. Then the following pairs of corresponding angles are equal.
1. Ð A = Ð E
2. Ð D = Ð H
3. Ð B = Ð F
4. Ð C = Ð G
Theorem  II:
If a transversal intersects two parallel lines, then the alternative angles are equal.
Hypothesis:
Two parallel lines 'l' and 'm' are intersected by a transversal 'p'.
ÐC, ÐE and ÐD, ÐF are the two pairs of alternative angles formed.
Conclusion:
a. ÐC = ÐE.
b. Ð D = ÐF.
Proof:
We know that ÐC and ÐB form a linear pair (Pair of angles formed on a straight line) and ÐE and ÐF also formed a linear pair.
Therefore, ÐC + ÐB = 180°
and ÐE + ÐF = 180°
Therefore, ÐC + Ð B = ÐE + ÐF
But Ð B = Ð F (by the axiom of corresponding angles).
Therefore, ÐC = ÐE [By cancelling equal angles ÐB and ÐF both sides].
Therefore, similarly we can be shown that ÐD = ÐF.
Directions: Draw parallel lines and a transversal and show corresponding angles and alternate angles.
