Answer with Step-by-step explanation:
The area of trapezoid is given by:
A=[tex]\dfrac{1}{2}\times (sum\ of\ bases)\times height[/tex]
Here we are given Area=390 km²
Sum of bases=(23+29) km
= 52 km
We have to find the height of trapezoid
Putting all the given values in the formula of area of trapezoid
[tex]390=\dfrac{1}{2}\times 52\times height[/tex]
390=26×height
height=15
Hence,height of trapezoid is:
15 km