Yes - they have to be similar. Since they are using the same line as the hypotenuse, the ratio of the other two sides are in the same ratio (ie, the slope of the line), the 3 inner angles will be the same. Thus, the triangles will be similar.
Since the center is considered the corner that they both share, here are the answers figure a goes with the first, figure b goes with the last, figure c goes with the second, and figure d goes with the third. Hope this helps.
You keep the same sign. So:-
4 + 4 = 8 and
--4 + -4 = -8
Answer:
m = 
Step-by-step explanation:

4
4*3 is 12 but 4 is not a multiple of 6