Double Angle Identity

Use a double-angle formula to rewrite each expression so that there are no multiple angles.

Use a double-angle formula to rewrite each expression so that there are no multiple angles.

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

Using the third identity, find Cos(40)

• 2cos² (40) - 1

• 2cos² (20) - 1

• 2cos² (20) + 1

• 2cos² (40) + 1

Using the first identity, find Sin(180)

• 2sin(90)cos(90)

• 2sin(180)cos(180)

• sin(90)cos(90)

• sin(180)cos(180)

Using the second identity, find Cos(50)

• sin²(25) - cos²(25) 

• cos²(50) - sin²(50)

• cos²(25) - sin²(25)

• sin²(50) - cos²(50) 

Simplify using double angle identities

• A

• B

• C

• D

Simplify using double angle identities

• A

• B

• C

• D

Simplify using double angle identities

• A

• B

• C

• D