Answer:
4 congruent triangles
Step-by-step explanation:
since there is no one of the sum of two sides is less then the third side, so it's possible to form a triangle
Use straightedge and compass, it can draw 4 triangles at a common base
Answer:
See below
Step-by-step explanation:
The initial ordered-pairs are 
We have a rotation of 90 degrees counterclockwise with respect to origin
Note. Previously the points were

After the rotation, we have

Thus, 
Then shifting horizontally to the right 2 units, we get ΔA'B'C'
Thus,

Answer:
10.5
Step-by-step explanation: