Answer:
x = 10
Step-by-step explanation:
Use Pythagorean theorem to find the value of x
Focus only on one half of the triangle
if we slice the triangle in half, we get a right angle triangle
the base will now be 12/2 = 6
Pythagorean theorem says that 
plug 6 as a and 8 as b.
this should give you 100
now take the square root to find c (which equals x)
Ta-da!
Answer:
A 1759 sq. units
Step-by-step explanation:
to find the surface area of a closed cylinder the formula is
2πr² + πdh
r = radius = 10
d = diameter = 10 + 10 = 20
2 x 3.14 x 10² + 3.14 x 20 x 18
628.3 + 1130.94 = 1759.24
ans = 1759