Note; if you have any more questions about this let me know in the comments and I’ll try to help you understand more.
PART A:
Alright bud, let’s start with angle #1. We should know by now that the angle measure of a straight line is 180 degrees, and that if there are two angles on a line then the measures of those two angles must measure up to 180 degrees.
Since we know that one angle is 92 degrees, what we’ll do is actually subtract 92 from 180. Since those two angles are guaranteed to add up to 180, it makes logical sense that we can just get rid of the measure of one of those angles and be left with the measure of the other angle. Since 180 - 92 is 88, we now know that the measure of Angle #1 is 88 degrees. Then, if we go back and look at it; it makes sense, doesn’t it? An 88 degree angle should be just a little bit smaller than a 90 degree angle, and it does look like that so we know our answer is correct.
Hopefully, you’ve learned by now that the angle sum of a triangle is 180 degrees. Since we know the measure of two of the angles — 88 degrees and 57 degrees — we can calculate the measure of the third angle.
First, we add the measures of the angles we already know.
88 + 57 = 145.
Now we know that since the angle sum of a triangle is 180, we can subtract 145 from 180 to get the third angle.
180 - 145 = 35.
Now, we figured out the angle of angle 2 and we know it’s 35 degrees.
It’s not too hard to calculate angle 3 at this point!
We’ll go back to the strategy we used to calculate angle 1. Since there are two angles on a straight line, we know they have to add up to 180.
Since Angle 2 is 35 degrees...
180 - 35 = 145.
We have now discovered that the measure of Angle 3 is 145 degrees.
<1 = 88 degrees
<2= 35 degrees
<3 = 145 degrees.
PART B:
Angle 1 is related to the exterior 123 degree angle in that they are both exterior, supplementary angles and their values can both be calculated using the triangle as reference.
This is the same for Angle 2.
(I’m not certain on this answer to Part B so try your hardest and see what makes sense.)