Step by step
The question
Question: find out if the two lines are parallel.
The corresponding angles are 3x and 2x + 25, with x = 25.
1 Put x in
Put x = 25 in the angle 3x.
3x = 3 × 25
That is 75°.
3x = 75
Put x = 25 in the angle 2x + 25.
2x + 25 = 2 × 25 + 25
That is 75°.
2x + 25 = 75
2 Name the angle pair
A line crosses two other lines.
It is called a transversal.
Our two angles are in the same place at each crossing: corresponding angles.
Together they make an F shape.
3 Use the parallel test
If the lines are parallel, both crossings look the same, so corresponding angles are equal.
And if they are equal, the lines are parallel.
75° and 75°: they are equal.
75 = 75
Careful!
For corresponding angles we ask: are they equal?
Careful: corresponding: equal, not adding to 180°
So the lines are parallel.
Answer: = parallel
We can draw the arrows on the lines now.
Let's look back.
First: put x in.
Then: name the angle pair.
Last: use the parallel test.
Answer
Answer: = parallel