Solving Double Angle Equations

If cosx = - 4/5, find csc if in quadrant II

• 1/2
• -3/5
• 5/3
• √3/2

expand
cos(2θ)

• cos²θ-sin²θ
• 2sinθcos
• 2cos²+1
• sin²θ-1

expand
sin(2θ)

• ½sinθ/cosθ
• sinθcosθ/2
• 2sinθcosθ
• 2sin²θ-cos²θ

expand 
tan(2θ)

• 2cos²θ/1-sin²θ
• sin²θ/cos²θ
• 2tanθ/1-tan²θ
• 2/cotθ+tanθ

Use a double-angle or half-angle identity to find the exact value of each expression
sin θ = −3/5 in Quadrant 4. Find tan θ/2

• -1/3
• -√3
• √3/3
• -1

Use a double-angle or half-angle identity to find the exact value of each expression
cos θ = 4/5 and is located in the fourth quadrant. Find sin 2θ

• -1/5
• 24/25
• -24/25
• -25/24

Use a double-angle identity to find the exact value of each expression
sin θ = −3/5 and is located in the fourth quadrant. Find tan 2θ

• -24/7
• 24/7
• 1
• -1
  -3/4

Use a double-angle or half-angle identity to find the exact value of each expression;
tan π/8.

• 1/2
• √3
• -√2 - 1
• 1

Use a half-angle identity to find the exact value of each expression
cos 165⁰

• -√(2+√3) / 2
• -√3/2
• √2 - 1
• √(3 - √2) -1

Use a double-angle or half-angle identity to find the exact value of each expression
cos θ = 4/5 and 270° < θ < 360°Find sin 2θ

• -1/5
• 24/25
• -24/25
• -25/24