segment addition postulate solve for x calculator

I like to show this slide to clarify that over and over! (Check out proof writing in more detail here.) Otherwise, when we lead into proof writing, I see angles being added instead of angle MEASURES being added.

I always feel like I cannot possibly over-reinforce the fact that measurements can be equal, whereas segments are congruent. I also do not allow explanations that say 'the yellow piece plus the pink piece.' Students must say that 'the length of the yellow piece plus the length of the pink.' It is so crucial that students do not write that the pink piece is 'equal to' the green one. This is a great opportunity to zero in on properties and vocabulary. When students think they have a great explanation, allow them to share it out loud with the class. It only takes a minute, and does not require a formal worksheet. Then, have them write it out (just in a notebook or on scrap paper for something like this).

Yes, it's obvious, but require each pair to come up with a very clear explanation of WHY.

Now what if I told you that the yellow and blue pieces are also the same length? What could you conclude about the green and pink pieces. Just say 'Without measuring, I can tell you you may assume that both of these new 'straws' are the same length. For something this quick, I like to keep it as a full-class guided inquiry.

Segment addition postulate solve for x calculator