Math Help!! 9th Grade?

[Victoria]

Please help me solve these problems... but not just help explain also so that I would be able to understand next time

Find the length of the line segment that joins the points.
1) (-2,-1) and (6,4)
2) (-1,2) and (-1,-3)
3) (2,3) and (-7,3)
4)(a,c) and (a+b,c)

[shhrewd]

For all of these, find the difference between the x's and y's and use pythagorean theorem.
1) Difference between -2 and 6 is 8. So, a=8
Difference between -1 and 4 is 5. So, b=5
a^2+b^2=c^2
64+25=c^2
c= sqrt 89
Use this method to solve the other problems.