trig identities

• $sin θ$


  $1 / csc θ$
• $csc θ$


  $1 / sin θ$
• $cos θ$


  $1/sec θ$
• $tan θ$


  $sin θ/cos θ =$$1/cot θ$
• $cot θ$


  $cos θ/sin θ =$$1/tan θ$
• Pythagorean Identity

  $sin^2 θ +$$cos^2 θ =$$1$
• $tan^2 θ +$$1$


  $sec^2 θ$
• $cot^2 θ+$$1$


  $csc^2 θ$
• $sin(α + β )$


  $sin(α)cos(β ) +$$cos(α)sin(β)$
• $sec θ$


  $1 / cos θ$
• $sin(α-β )$


  $sin(α)cos(β)-cos(a)sin( β)$
• $cos(α+β)$


  $cos(a)cos(β)-sin(a)sin(β)$
• $cos(α-β)$


  $cos(α)cos(β) +$$sin(α)sin(β)$
• $sin 2 θ$


  $2sin θcos θ$
• $cos 2 θ$


  $cos^2 θ-sin^2 θ=$$2cos^2 θ-1=$$1-2sin^2 θ$
• $cos^2 θ$


  $1 +$$cos2 θ / 2$
• $sin^2 θ$


  $1-cos2 θ/2$