1. Enter To show the dynamic figures properly, the evaluation version of Cabri 3D (V2.0 or above) must be installed.

2. There are 12 multiple choice questions. Click the letter to answer. Enter

3. ABCDEFGH is a cube. Which of the following angle is the angle between planes ABGH and ABCD? A  CAG B  CBG C  CGB D  DBH 1. (Hold down the right mouse button and drag to change the view angle.)

4. Back 1. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes ABGH and ABCD?

5. Next  CBG is the angle between planes ABGH and ABCD. (Click and right-button drag the figure to change the view angle. ) 1. Correct!

6. ABCDEFGH is a cuboid. Which of the following angles is the angle between planes ABGH and CDHG? B  AGC C  AHD A  DHB D  HAD 2. (Hold down the right mouse button and drag to change the view angle.)

7. Back 2. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes ABGH and CDHG?

8. Next 2. Correct!  AHD is the angle between planes ABGH and CDHG. (Click and right-button drag the figure to change the view angle. )

9. B  OCV C  OMV A  OBV D  OVM ABCD is a square, M is the mid-point of BC, and VO is the altitude of the pyramid. Which angle is the angle between planes VBC and ABCD? 3. (Hold down the right mouse button and drag to change the view angle.)

10. Back 3. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes VBC and ABCD?

11. Next 3. Correct!  OMV is the angle between planes VBC and ABCD. (Click and right-button drag the figure to change the view angle. )

12. ABCD is a square, N is the mid-point of AB, and VO is the altitude of the pyramid. Which of the following angles is the angle between planes VAB and ABCD? B  OAV C  OBV A  ONV D  ABV 4. (Hold down the right mouse button and drag to change the view angle.)

13. Back 4. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes VAB and ABCD?

14. Next  ONV is the angle between planes VAB and ABCD. (Click and right-button drag the figure to change the view angle. ) 4. Correct!

15. In the figure CO is the altitude of the pyramid,  AOB = 90 , M is the mid-point of AB, OP  AB. Which of the following angles is the angle between planes ABC and OAB? B  OPC C  OAC A  OMC D  OBC 5. (Hold down the right mouse button and drag to change the view angle.)

16. Back 5. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes ABC and OAB?

17. Next  OPC is the angle between planes ABC and OAB. (Click and right-button drag the figure to change the view angle. ) 5. Correct!

18. B  OCB C  ONB A  OAB D  OQB In the figure CO is the altitude of the pyramid,  AOB = 90 , N is the mid-point of AC, OQ  AC. Which of the following angles is the angle between planes ABC and OAC? 6. (Hold down the right mouse button and drag to change the view angle.)

19. Back 6. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes ABC and OAC?

20. Next  ONV is the angle between planes ABC and OAC. (Click and right-button drag the figure to change the view angle. ) 6. Correct!

21. B  ACB C  OCA A  AOB D  OCB In the figure, CO is the altitude of the pyramid,  AOB = 90 . Which of the following angles is the angle between planes OAC and OBC? 7. (Hold down the right mouse button and drag to change the view angle.)

22. Back 7. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes ABGH and ABCD?

23. Next  AOB is the angle between planes OAC and OBC. (Click and right-button drag the figure to change the view angle. ) 7. Correct!

24. In the prism of the figure, ABCD and CDEF are rectangles,  BCF = 90 . Which of the following angles is the angle between planes ABFE and ABCD? B  AED C  EAB A  DAE D  FAC 8. (Hold down the right mouse button and drag to change the view angle.)

25. Back 8. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes ABFE and ABCD?

26. Next  DAE is the angle between planes ABFE and ABCD. (Click and right-button drag the figure to change the view angle. ) 8. Correct!

27. B  DAE C  DEA A  AEF D  ADE In the prism of the figure, ABCD and CDEF are rectangles,  BCF = 90 . Which of the following angles is the angle between ABFE and CDEF? 9. (Hold down the right mouse button and drag to change the view angle.)

28. Back 9. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes ABFE and CDEF?

29. Next  DEA is the angle between planes ABFE and CDEF. (Click and right-button drag the figure to change the view angle. ) 9. Correct!

30. B  DAH C  DCH A  HAC D  DOH ABCDEFGH is a cube, O is the centre of ABCD. Which of the following angles is the angle between planes ACH and ABCD? 10. (Hold down the right mouse button and drag to change the view angle.)

31. Back 10. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes ACH and ABCD?

32. Next 10. Correct!  DOH is the angle between planes ACH and ABCD. (Click and right-button drag the figure to change the view angle. )

33. In the figure, ABCD is a rectangle, M is the mid-point of AB, and VD is the altitude of the pyramid. Which of the following angles is the angle between planes VAB and ABCD? B  VMD C  VBA A  VAD D  VBD 11. (Hold down the right mouse button and drag to change the view angle.)

34. Back 11. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes VAB and ABCD?

35. Next 11. Correct!  VAD is the angle between planes VAB and ABCD. (Click and right-button drag the figure to change the view angle. )

36. B  VND C  VCD A  VBD D  VBC In the figure, ABCD is a rectangle, N is the mid-point of BC, and VD is the altitude of the pyramid. Which of the following angles is the angle between planes VBC and ABCD? 12. (Hold down the right mouse button and drag to change the view angle.)

37. Back 12. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes VBC and ABCD?

38. End Restart 12. Correct!  VCD is the angle between planes VBC and ABCD. (Click and right-button drag the figure to change the view angle. )

39. B  BVD C  AVC A  BVC D  AVD In the figure, ABCD is a rectangle, VD is the altitude of the pyramid. Which of the following angles is the angle between planes VAB and VCD? 13. (Hold down the right mouse button and drag to change the view angle.)

40. Back 13. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes VAB and VCD?

41. Next 13. Correct!  AVD is the angle between planes VAB and VCD. (Click and right-button drag the figure to change the view angle. )

42. B  CBH C  OBA A  ABF D  OBD The figure shows a right square prism, O is the centre of EFGH. Which of the following angles is the angle between planes BFH and ABCD? 14. (Hold down the right mouse button and drag to change the view angle.)

43. Back 14. Incorrect! Hint: Click and right-button drag the figure to change the view angle. Which angle is the angle between planes BFH and ABCD?

44. 14. Correct!  OBD is the angle between planes EFH and ABCD. (Click and right-button drag the figure to change the view angle. )