Trig Identities

Which of these is equivalent to 2cos²x − 3cosx = 0 ?

• -cos²x = 0

• cosx(2cosx + 3) = 0

• cosx(2cosx − 3) = 0

• cos x = ⅔

• I have no idea

Tags

CCSS.HSF.TF.B.7

Why doesn't 2cosx − 3 = 0 have solutions?

• cosx is never bigger than one

• cosx is never equal to a fraction

• Actually, this equation does have a solution, x = π

• This equation will have a solution tomorrow.

• I have no idea

Tags

CCSS.HSF.TF.B.7

Choose a good way to start solving this equation

tanx sin²x = 2 tanx

• divide tanx from both sides

• factor out tanx

• subtract 2 tanx from the left and then factor tanx out

• cancel sin²x out

• I have no idea

Tags

CCSS.HSF.TF.B.7

Factor 0 = sin²x − sinx

• 0 = sinx(sinx)

• 0 = sinx(1 − sinx)

• 0 = cosx(sinx − 1)

• 0 = sinx(sinx − 1)

• I have no idea

Tags

CCSS.HSF.TF.B.7

On the interval [0, 2π), solve this equation 0 = sinx(sinx − 1)

• 0, π

• 0, π, ½π

• ½π

• 0^o, 90^o, 270^o

• I have no idea

Tags

CCSS.HSF.TF.B.7

csc²x = 2 is equivalent to sin²x = ½

• True

• False

• I have no idea

Tags

CCSS.HSF.TF.B.7

Factor: sec²x − secx − 2

• (sec x)(secx − 2)

• (secx − 2)(secx − 1)

• (secx − 2)(secx + 1)

• (secx + 2)(secx − 1)

• I have no idea

Tags

CCSS.HSA.APR.C.4

Simplify sec²(x) - tan²(x)

• tan(x)

• 1

• -sin(x)

• -1

• I have no idea

Tags

CCSS.HSF.TF.C.8

Simplify (sec²x)(1 - sin²x)

• -cos(x)

• 1

• -1

• -sin(x)

• I have no idea

Tags

CCSS.HSF.TF.C.8

Simplify cot(x)tan(x) + cot²(x)

• -cot(x)

• csc²(x)

• sec(x)

• -csc²(x)

• I have no idea

Tags

CCSS.HSA.APR.D.6

CCSS.HSA.APR.D.7

CCSS.HSA.SSE.B.3