Question

PLZ HELP ASAP SOLID GEOMETRY

Answer 1

D.
first of all we know if a half circle rotates 360°we will get a sphere, with a quarter circle, we will get a semi sphere. therefore we can eliminate choices A and B
with the diagram, the radius is 5, the diameter is 5*2=10 which means D is the correct answer

Answer 2

For this case we have that the radius of the quarter circle is given by:
 r = 5 units
 Rotating the quarter circle produces a hemisphere (half of a sphere).
 The diameter of the hemisphere is given by:
 d = 2r
 d = 2 (5)
 d = 10 units
 Answer:
 option D