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interior angles are supplementary
Practice Set 2.2
Choose the correct alternative
(1) In the adjoining figure, if line m ll linen
and line p is a transversal then find
(A) 135° (B) 90° (e) 45°
(D) 40
(2) In the adjoining figure, if line all line b
and line is a transversal then find .x.
(A) 90° (B) 60°
(C) 45°
(D) 30°
2x
P
2. In the adjoining figure line pll line q.
Line 1 and line s are transversals.
Find measure of Zx and Zy
using the measures of angles given
in the figure
70
11
Answers
Answer:
Two lines that are stretched into infinity and still never intersect are called coplanar lines and are said to be parallel lines. The symbol for "parallel to" is //.
If we have two lines (they don't have to be parallel) and have a third line that crosses them as in the figure below - the crossing line is called a transversal:
Transversal
In the following figure:
Angles
If we draw to parallel lines and then draw a line transversal through them we will get eight different angles.
The eight angles will together form four pairs of corresponding angles. Angles F and B in the figure above constitutes one of the pairs. Corresponding angles are congruent if the two lines are parallel. All angles that have the same position with regards to the parallel lines and the transversal are corresponding pairs.
Angles that are in the area between the parallel lines like angle H and C above are called interior angles whereas the angles that are on the outside of the two parallel lines like D and G are called exterior angles.
Angles that are on the opposite sides of the transversal are called alternate angles e.g. H and B.
Angles that share the same vertex and have a common ray, like angles G and F or C and B in the figure above are called adjacent angles. As in this case where the adjacent angles are formed by two lines intersecting we will get two pairs of adjacent angles (G + F and H + E) that are both supplementary.
Two angles that are opposite each other as D and B in the figure above are called vertical angles. Vertical angles are always congruent.