Half Angle Identities

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

Use a double-angle or half-angle identity to find the exact value of each expression
sin θ = −3/5 and 3π/2 < θ < 2π 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 270° < θ < 360°Find sin 2θ

• -1/5

• 24/25

• -24/25

• -25/24

Use the Half-angle formulas to find the exact value of each expression
sin 22.5º

sin u/2 =

tan u/2 =

cos u/2 =

Using the third identity, find Cos(40)

• 2cos² (40) - 1

• 2cos² (20) - 1

• 2cos² (20) + 1

• 2cos² (40) + 1