1. By S.V. Cunningham Three Rivers Community College
Double Angle Formulas
By S.V. Cunningham
Three Rivers Community College

4. Let sinA=1/5 with A in QI. Find sin(2A).

5. Let sinA=1/5 with A in QI. Find sin(2A).

6. Let sinA=1/5 with A in QI. Find sin(2A).

7. Find sin(90°) using a double angle formula.

8. Simplify 2sin30°cos30°.

11. Simplify cos215°–sin215°.

12. Derive an alternative form of the identity cos(2A)=cos2A–sin2A.

13. Derive an alternative form of the identity cos(2A)=cos2A–sin2A.

14. The identity with its alternative forms.

15. Suppose that cos x =1/ 10 with xQ IV, find sin(2x) and cos(2x).

16. Suppose that cos x =1/ 10 with xQ IV, find sin(2x) and cos(2x).

17. Suppose that cos x =1/ 10 with xQ IV, find sin(2x) and cos(2x).

18. Suppose that cos x =1/ 10 with xQ IV, find sin(2x) and cos(2x).

19. Simplify 2cos2105°–1.

20. Prove that (cos x – sin x)(cos x + sin x)=cos(2x)

37. Derive a double angle formula for the tangent function.

38. Derive a double angle formula for the tangent function.

39. Derive a double angle formula for the tangent function.

40. Derive a double angle formula for the tangent function.

41. Derive a double angle formula for the tangent function.

42. Derive a double angle formula for the tangent function.

43. Derive a double angle formula for the tangent function.

44. Derive a double angle formula for the tangent function.

45. Derive a double angle formula for the tangent function.

46. Derive a double angle formula for the tangent function.

47. Derive a double angle formula for the tangent function.

48. Derive a double angle formula for the tangent function.

49. Derive a double angle formula for the tangent function.

50. Derive a double angle formula for the tangent function.

51. Given cos  =1/10 and x  QIV, find tan(2).

52. Given cos  =1/10 and x  QIV, find tan(2).

53. Given cos  =1/10 and x  QIV, find tan(2).

55. Given csc t = 7 with t in QII, find sin(2t) and cos(2t).

56. Given csc t = 7 with t in QII, find sin(2t) and cos(2t).

57. Given csc t = 7 with t in QII, find sin(2t) and cos(2t).