Cube and Pic

Chapter 4 Study of 3-dimensional Figures

Multiple Choice Questions

1. Which of the following is a right pyramid? I. [pic] II. [pic] III. [pic] IV. [pic]

A. II only

B. III only

C. II, III and IV only

D. I, II, III and IV

1. A The base of a pyramid must be a polygon. Also, if all the slant edges of a pyramid are same in length, this pyramid is called a right pyramid. ∴ II is a right pyramid.

2. If O is the foot of perpendicular of the vertex V of a nonagonal pyramid, find the angle between the straight line VO and the base.

A. 17(

B. 20(

C. 90(

D. 180(

2. C ∵ VO is perpendicular to the base. ∴ The angle between straight line VO and the base is 90(.

3. Which of the following are correct? I. The base of a right triangular pyramid is a triangle. II. The lateral face of a right rectangular pyramid is a triangle. III. The lateral face of a right regular pentagonal pyramid is a regular pentagon.

A. I only

B. II only

C. I and II only

D. I, II and III

3. C ∵ A right pyramid is named according to the shape of its base. ∴ I is correct. ∵ Each lateral face of a right pyramid is a triangle. ∴ II is correct and III is incorrect.

4. How many planes of reflection are there in a right regular 21-gonal pyramid?

A. 21

B. 22

C. 23

D. 24

4. A There are 21 planes of reflection in a right regular 21-gonal pyramid.

5. How many planes of reflection are there in a right regular 19-gonal prism?

A. 19

B. 20

C. 21

D. 22

5. B There are 20 planes of reflection in a right regular 19-gonal prism.

6. If a solid has 8-fold rotational symmetry about the axis PQ, what should be the smallest angle of rotation of