Answer: Choice A. sqrt(116)
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Explanation:
If we were to view a vertical cross section of the cone, then we get a triangle. This triangle splits along the vertical height line to form two congruent right triangles.
The horizontal piece of each triangle is the radius r = 4.
The vertical piece is the height h = 10.
Apply the pythagorean theorem to find the slant height, which is the hypotenuse of the right triangle.
a^2 + b^2 = c^2
r^2 + h^2 = x^2
4^2 + 10^2 = x^2
16 + 100 = x^2
116 = x^2
x^2 = 116
x = sqrt(116)
