This is a free lesson from our course in Geometry

 In this lesson you’ll learn about how to identify Special Angle Pairs. The presentation by the instructor will be done in own handwriting, using video and with the help of several examples with solution. It will be followed by explaining their use to help you solve problems. Before proceeding to look into the explanations, you may recall from earlier learning on basics of interior, exterior, and alternate angles etc. In the below diagram, and are the coplanar lines and a transversal intersects at P and Q. The angles formed are 1 to 8 as shown in the figure below. Now on you’ll learn how some of the angles can be paired together in relation to their locations. (More text below video...)
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(Continued from above) Such paired angles are represented by special names and identified accordingly. In this case For Example:
• two pairs of interior angles (4 and 5) & (3 and 6) are formed on the same side of transversal.
• two pairs of alternate angles (4 and 6) & (3 and 5) are formed. Such pair will be considered alternate angles only if- both are interior angles and opposite sides of the transversal, but should not be adjacent angles.
• four pairs of corresponding angles [(1 and 5), (4 and 8), (2 and 6) & (3 and 7) are formed. Such pairs will be considered corresponding angles only if- they are on the same side of transversal, but not adjacent angles. In addition, one is the interior angle, the other one being exterior angle.
Remember:
Two lines cut by a transversal are parallel if and only if:
• alternate interior angles are equal in measure, or
• alternate exterior angles are equal in measure, or
• corresponding angles are equal in measure.
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