Here are a few reasons:
The triangles have the same three sides
The triangles have the same three angles
The triangles could perfect overlap one another
They have corresponding angles.
Not sure if this helped but I hope so!
Answer:
The radius is: 
Step-by-step explanation:
The equation of a circle in center-radius form is:

Where the center is at the point (h, k) and the radius is "r".
So, given the equation of the circle:

You can identify that:

Then, solving for "r", you get that the radius of this circle is:

Answer:
5. 2
6. 10
i hope these are right!
Step-by-step explanation:
Answer: it may be 85 but i didnt get anything else
Answer: slope = 3
Step-by-step explanation:
We can see from the point intersecting the y axis (y-intercept) to the point (1, 1) it goes up 3 and right 1 giving us the slope
simplified to 3