Answer:
Yes
Step-by-step explanation:
You can test if a triangle is right-angled by using Pythagoras' Theorem.
So:

16 + 56.25 = 72.25
They do in fact add up so this triangle is right angled.
Step-by-step explanation:
1.Draw a triangle
2. Measure one of the sides of the triangle
3. Place a point at the midpoint of one of the sides of the triangle.
4. Draw a line segment from the midpoint to the opposite vertex. The segment you just created is called a median.
5. Repeat steps 2-4 for the remaining two sides of the triangle.
-17 - (-8)
You are subtracting -17 by -8.