Pre-Calc Double Angle Identities

Use a double-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 identity to find the exact value of each expression

sin θ = −3/5 and 3π/2 < θ < 2π Find tan 2 θ

• -12/7

• -√3

• √3/3

• -1

Find the exact value of sin 2x if sin x = 12/13 and x is in the first quadrant. 

• 120/169
• 25/169
• 60/169
• 5/13

Use the information about the angle θ, 0≤θ<2π to find the exact value of
sin (2θ)
1. sin θ= 3/5 , 0<θ<π/2

• 24/7
• 7/25
• 24/25
• 1/2

sin2u =

• (sinu)(cosu)
• 2(sinu)(cosu)
• (sinu)^2
• 2(sinu)^2

cos2u =

• 2(sinu)(cosu)
• (cosu)^2 - (sinu)^2
• 2(cosu)^2 - 2
• (sinu)^2 - (cosu)^2

If cosx = - 4/5, find secx.

• -5/4

• -3/5

• 5/3

• √3/2

Find the exact value of sin 2x if sin x = 12/13 and x is in the first quadrant. 

• 120/169
• 25/169
• 60/169
• 5/13

Use a double-angle identity to find the exact value of each expression

sin θ = -4/5 and 270° < θ < 360°

Find cos 2θ

• -1/5

• 24/25

• -7/25

• -25/24

Which identity represents a double-angle identity for sin 2θ?

• 2sinθcosθ
• cos²θ - sin²θ
• 1 - 2sin²θ
• 2cos²θ - 1