Answer:
Let me know if there is anything you don't get
∠3 = 102 because ∠1 and ∠3 are supplementary and 102 + 78 = 180
∠4 = 102 because ∠1 and ∠4 are consecutive interior angles
∠5 = 78 because ∠1 and ∠5 are corresponding angles
∠6 = 133 because ∠2 and ∠6 are supplementary angles
∠7 = 47 because ∠2 and ∠7 are vertical angles
∠8 = 47 because ∠2 and ∠8 are opposite interior angles
∠9 = 133 because ∠8 and ∠9 are supplementary, and we just saw ∠2=∠8
∠10 = 102 because ∠1 and ∠10 are supplementary
You could have used a whole bunch of different relations, but I wanted to focus on ∠1 and ∠2 since those were told to us
Step-by-step explanation:
For this question you need to know several parts of geometry. Let me know if anything doesn't make sense.
First, parallel lines are two or more lines which are angles in such a way that no matter how long they are they will not cross. In other words they are slanted at the same angle. you can see this with lines a and b in this picture.
Second, a transversal is a line that crosses through two or more parallel lines. A transversal creates a number of angles that have special properties. I would like you to look specifically at line c as I describe these angles. line c is a transversal to Ines a and b. Also line d is also a transversal.
There are seven special angles to know.
The easiest is supplementary angles. This you don't need parallel lines, but if any two lines ever cross this creates 4 angles. you can actually look at where lines c and b intersect in your problem. Angles 2. 6 and 7 are labeled but there is one more unlabeled one. Now, 180 degrees is a straight line. With angles you can see angles 6 and 7 add together to be a straight line. Similarly 2 and 6 do as well. These are two sets of supplementary angles.
To list off the supplementary angles here 9 and 8 are supplementary, as are 2 and 6, 6 and 7, 1 and 3, 1 and 10, and finally 4 and 5.
From supplementary angles comes vertical angles. Again, if you look at angles 2, 6 and 7 we already know ∠2 + ∠6 = 180 and ∠6 + ∠7 = 180. Well lets say ∠6 = 133. Well then, we could use algebra to see that both ∠2 AND ∠7 are 47 degrees. This is the property of vertical angles. if you have two lines intersecting, any two angles that have a third in between the are called vertical angles, and are equal.
some examples of vertical angles are ∠2 and ∠7as well as ∠3 and ∠10,
Finally we go into parallel line specific angles. If you have two or more parallel lines with a transversal, so in particular look at a and b as the parallel lines and c as the transversal. The transversal creates some special angles. in particular, the transversal crosses a and b at the same angle, so angles 8 and 7 have the same value. These are known as corresponding angles, since they correspond tot he same position with a transversal crossing through parallel lines.
the corresponding angles in the picture are ∠8 and ∠7, ∠3 and ∠4 and finally ∠1 and ∠5. the last two using line d as a transversal.
After corresponding angles opposite interior angles I think are the next logically to look at. Opposite means they are on two different parallel lines and on different sides of the transversal, while interior means they are between the parallel lines. so if you look at the parallel lines a and b there are angles 8 and 2 that are interior angles. Since 8 is against line a and 2 is against line b, and ∠8 is above transversal c while ∠2 is below it, they are opposite angles. so 8 and 2 are opposite interior angles. Now, if you look at ∠8 and ∠7 you know these are corresponding angles, then ∠7 and ∠2 are vertical angles. This means opposite interior angles are equal.
A list of opposite interior angles are ∠8 and ∠2, and ∠10 and ∠4.
Alongside opposite interior, there are opposite exterior angles. opposite means on different parallel Ines and on opposite sides of the transversal, while this time exterior means not between the parallel lines. Now just like we figured with opposite interior angles
The only labeled pair of opposite exterior angles are ∠9 and ∠6. Now just like we figured with opposite interior angles, let's start with ∠8 and ∠9, which are supplementary. then ∠8 and ∠7 are corresponding angles so ∠9 and ∠7 are supplementary. We can also see ∠7 and ∠6 are supplementary. well, since ∠9 + ∠7 = 180 = ∠6 + ∠7 then ∠9 = 180 - ∠7 = ∠6 so ∠9 = ∠6. This shows opposite exterior angles are equal.
So we did two kinds of opposite angles, it might make sense there are non opposite angles. And there are. these are called consecutive angles. There are consecutive exterior and consecutive interior angles. An example of each are ∠1 and ∠4 for consecutive interior, consecutive because they are on the same side of the transversal, and interior because they are between the two parallel lines. ∠3 and ∠5 are consecutive exterior angles.
You can use similar reasoning we have been so far to conclude all consecutive angles are supplementary
