Justify the last 2 steps. given: rs=ut and rt=us prove rst=uts proof: 1. rs=ut given 2. rt=us given 3. st=ts ? rst=uts ?

The third step is based on the symmetric property of a segment, which says that a segment is congruent to itself, no matter the position of the points, therefore a segment is congruent to .

The fourth step is about the congruence between those two triangles. Basically, in the problem, it can be deducted that congruence because all corresponding sides are congruent, that is,

So, basically we use the SSS postulate, that is, Side-Side-Side, which states that if two triangles have congruent corresponding sides, then those triangles are congruent.

From the SSS postulate, we deduct that angles are also congruent.

12

step-by-step explanation:

12 + 5 = 17

12x2=24

24-7=17