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Lesson Example Discussion Quiz: Class Homework

Step-5

Title: Parallel Lines

Grade: 6-a Lesson: S2-L7

Explanation: Hello Students, time to practice and review the steps for the problem.

Lesson Steps

Step	Type	Explanation	Answer
1	Problem	If lines C and D are parallel, and angle 1 is 51 degrees as an alternate exterior angle, what is the measure of angle 7 in this situation?
2	Step	In the given picture lines C and D are parallel so the corresponding angles are equal	⇒ ∠1 = ∠5, ∠2 = ∠6, ⇒ ∠3 = ∠7, ∠4 = ∠8
3	Hint	In the parallel lines the alternative exterior angles are equal, that is	∠1 = ∠8
4	Step	So the angle 8 is equal to 51°.
5	Step	The sum of angles 7and 8 are supplementary	∠7 + ∠8 = 180°
6	Step	Replace ∠8 with its numerical value, then simplify the expression	⇒ ∠7 + 51 = 180 ⇒ ∠7 = 180 - 51 ⇒ ∠7 = 129
7	Step	Angle 7, as measured 129°.
8	SumUp	Can you summarize what you’ve understood in the above steps?
9	Choice.A	This is not correct because they do not match the established measure of angle 7	125
10	Choice.B	It matches the measure of angle 7, which is 51 degrees, based on the properties of alternate exterior angles	129
11	Choice.C	This is not correct because they do not match the established measure of angle 7	139
12	Choice.D	This is not correct because they do not match the established measure of angle 7	119
13	Answer	Option	B
14	SumUp	Can you summarize what you’ve understood in the above steps?

Step

Type

Explanation

Answer

Problem

If lines C and D are parallel, and angle 1 is 51 degrees as an alternate exterior angle, what is the measure of angle 7 in this situation?

Step

In the given picture lines C and D are parallel so the corresponding angles are equal

⇒ ∠1 = ∠5, ∠2 = ∠6,
⇒ ∠3 = ∠7, ∠4 = ∠8

Hint

In the parallel lines the alternative exterior angles are equal, that is

∠1 = ∠8

Step

So the angle 8 is equal to 51°.

Step

The sum of angles 7and 8 are supplementary

∠7 + ∠8 = 180°

Step

Replace ∠8 with its numerical value, then simplify the expression

⇒ ∠7 + 51 = 180
⇒ ∠7 = 180 - 51
⇒ ∠7 = 129

Step

Angle 7, as measured 129°.

SumUp

Can you summarize what you’ve understood in the above steps?

Choice.A

This is not correct because they do not match the established measure of angle 7

125

Choice.B

It matches the measure of angle 7, which is 51 degrees, based on the properties of alternate exterior angles

129

Choice.C

This is not correct because they do not match the established measure of angle 7

139

Choice.D

This is not correct because they do not match the established measure of angle 7

119

Answer

Option

SumUp

Can you summarize what you’ve understood in the above steps?