Parallel Lines andthe Angles Formed
Slide 1
Vertically opposite
angles are equal.
Corresponding
angles are equal.
Same-side interior angles
are supplementary
(adds up to 180).
Alternate interior
angles are equal.
Same-side exterior angles
are supplementary
(adds up to 180).
Alternate exterior
angles are equal.
2.
Slide 2
Example 1:
Inthe diagram below, l1 is parallel to l2. State the measures of the
indicated angles and explain your reasoning.
3.
Slide 3
Example 1:
Inthe diagram below, l1 is parallel to l2. State the measures of the
indicated angles and explain your reasoning.
Lines 1 and 2 are parallel (given).
2 and 118 are supplementary
2 + 118 = 180
2 = 62
>
>
4.
Slide 4
Example 1:
Inthe diagram below, l1 is parallel to l2. State the measures of the
indicated angles and explain your reasoning.
Lines 1 and 2 are parallel (given).
2 and 118 are supplementary
2 + 118 = 180
2 = 62
3 and 118 are corresponding angles so
they are equal
3 = 118
>
>62
5.
Slide 5
Example 1:
Inthe diagram below, l1 is parallel to l2. State the measures of the
indicated angles and explain your reasoning.
Lines 1 and 2 are parallel (given).
2 and 118 are supplementary
2 + 118 = 180
2 = 62
3 and 118 are corresponding angles so
they are equal
3 = 118
1 and 71 are same-side interior angles
so they are supplementary (adds up to 180)
1 + 71 = 180
1 = 109
>
>62
118
6.
Slide 6
Example 1:
Inthe diagram below, l1 is parallel to l2. State the measures of the
indicated angles and explain your reasoning.
Lines 1 and 2 are parallel (given).
2 and 118 are supplementary
2 + 118 = 180
2 = 62
3 and 118 are corresponding angles so
they are equal
3 = 118
3 and 4 are supplementary
3 + 4 = 180
118 + 4 = 180
4 = 62
OR (alternate solution)
2 and 4 are corresponding
2 = 4 = 62
1 and 71 are same-side interior angles
so they are supplementary (adds up to 180)
1 + 71 = 180
1 = 109
>
>62
118
109
7.
Slide 7
Example 1:
Inthe diagram below, l1 is parallel to l2. State the measures of the
indicated angles and explain your reasoning.
Lines 1 and 2 are parallel (given).
2 and 118 are supplementary
2 + 118 = 180
2 = 62
3 and 118 are corresponding angles so
they are equal
3 = 118
3 and 4 are supplementary
3 + 4 = 180
118 + 4 = 180
4 = 62
OR (alternate solution)
2 and 4 are corresponding
2 = 4 = 62
1 and 71 are same-side interior angles
so they are supplementary (adds up to 180)
1 + 71 = 180
1 = 109
>
>62
118
109
62
8.
Slide 8
Example 2:
Aplumber must install pipe 2 parallel to pipe 1. He knows that 1
is 53. What is the measure of 2?
9.
Slide 9
Example 2:
Aplumber must install pipe 2 parallel to pipe 1. He knows that 1
is 53. What is the measure of 2?
Pipes 1 and 2 are to be parallel (given)
1 and 2 are same-side interior angles
Same-side interior angles are supplementary
1 + 2 = 180
53 + 2 = 180
2 = 127
Angle 1 is 53 (given)
In order for pipes 1 and 2 to be parallel, the measure of 2 should be 127
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>
53