Solving Trig Identities

cos2u =

• 2(sinu)(cosu)

• (cosu)² - (sinu)²

• 2(cosu)² - 2

• (sinu)² - (cosu)²

• I have no idea

Which of these are equal to 1? (Check all that apply)

• sin²(θ) + cos²(θ)

• sec²(θ) - tan²(θ)

• csc²(θ) - cot²(θ)

• tan²(θ) - cos²(θ)

Which identity does not represent a double-angle identity for cos 2θ?

• 2sinθcosθ

• cos²θ - sin²θ

• 1 - 2sin²θ

• 2cos²θ - 1

Write the following expression as the sine, cosine, or tangent of an angle.
cos(175)cos(55)+sin(175)sin(55)

• sin(120)

• cos(120)

• cos(230)

• sin(230)

Please choose the correct sum and difference formula:
sin (α-β) =

• sin α cos β + cos α sin β

• sin α cos β - cos α sin β

• cos α cos β - sin α sin β

• cos α cos β + sin α sin β

Please choose the correct sum and difference formula:
cos (α+β) =

• sin α cos β + cos α sin β

• sin α cos β - cos α sin β

• cos α cos β - sin α sin β

• cos α cos β + sin α sin β

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

• 2sinθcosθ

• cos²θ - sin²θ

• 1 - 2sin²θ

• 2cos²θ - 1

• -1

• sin θ

• csc θ

• 1

• secθ

• cos²θ

• sin²θ

• sin²θ/cos²θ

• sin²θ

• cosθ

• tanθ

• 1- sin²θ