Formula for lateral surface area of cone is:
![A = \pi r l]()
where l is length of diagonal or slant length of cone
![l = \sqrt{h^2 + r^2]()
The given figure shows a symmetric double cone, so we need to only find lateral surface area of one come then double it to get surface area or entire figure.
![A = 2 \pi r √(h^2 + r^2)]()
Now just sub in given values for radius and height:
r = 10, h = 24
![A = 520 \pi]()