Using Double-Angle Identities (7.6.2)

Question 1

• Double-angle identities can help you solve trigonometric equations.

Answer 1

• Double-angle identities can help you solve trigonometric equations.

Question 2

• The double-angle identities:
  
  • sin 2θ = 2 sinθ cosθ
  • cos 2θ = cos2θ – sin2θ
  • cos 2θ = 1 – 2sin2θ
  • cos 2θ = 2cos2θ – 1
  • tan 2θ = (2tanθ)/1-tan^2θ

Answer 2

• The double-angle identities:
  
  • sin 2θ = 2 sinθ cosθ
  • cos 2θ = cos2θ – sin2θ
  • cos 2θ = 1 – 2sin2θ
  • cos 2θ = 2cos2θ – 1
  • tan 2θ = (2tanθ)/1-tan^2θ