Question

practice 3
match the two - dimensional figure and axis of rotation with the solid of rotation that can be formed by rotating the figure, using that axis.
a: a cylinder
b: a sphere
c: a cone
1:
2:
3:

Explanation:

Step1: Analyze Figure 1 (Right Triangle)

A right triangle rotated about one of its legs (the axis here) forms a cone. So Figure 1 (1) matches with C: a cone.

Step2: Analyze Figure 2 (Rectangle)

A rectangle rotated about one of its sides (the axis here) forms a cylinder. So Figure 2 (2) matches with A: a cylinder.

Step3: Analyze Figure 3 (Semicircle)

A semicircle rotated about its diameter (the axis here) forms a sphere. So Figure 3 (3) matches with B: a sphere.

Answer:

A: a cylinder $\longleftrightarrow$ 2: (Rectangle)
B: a sphere $\longleftrightarrow$ 3: (Semicircle)
C: a cone $\longleftrightarrow$ 1: (Right Triangle)