Find the lengths of the diagonals of this trapezoid. when the given length for the sides are (-b,c), (b,c),(a,0), (a,0)

As drwls pointed out in your previous post below this one, you have a typo

I will assume that you missed a negative sign in your last point and it should have been (-a,0)

So the diagonals run from (-b,c) to (a,0) and
from (b,c) to (-a,0)

I will do one, you do the other,
first diagonal = √(a-(-b))^2 + (0-c)^2 )
= √(a^2 + 2ab + b^2 + c^2)

To find the lengths of the diagonals of a trapezoid, we can use the distance formula. The distance formula is:

Distance = √((x2 - x1)^2 + (y2 - y1)^2)

Let's label the points given as follows:
A = (-b, c)
B = (b, c)
C = (a, 0)
D = (a, 0)

To find the length of diagonal AC, we need to find the distance between points A and C:
AC = √((a - (-b))^2 + (0 - c)^2)

Simplifying this expression gives us:
AC = √((a + b)^2 + c^2)

Similarly, to find the length of diagonal BD, we need to find the distance between points B and D:
BD = √((a - b)^2 + (0 - c)^2)

Simplifying this expression gives us:
BD = √((a - b)^2 + c^2)

Therefore, the lengths of the diagonals AC and BD of the trapezoid are √((a + b)^2 + c^2) and √((a - b)^2 + c^2), respectively.