5.1
5.2
5.3
Identifying Identities
Trig Trivia
100

Simplify the Trig Expression:

tan(θ)cos(θ)


sin(θ)

100

(1 + cosx)/(sinx) = cscx + cotx

(1 + cosx)/(sinx) = 

(1/sinx) + (cosx/sinx) = 

cscx + cotx

100

Solve the Equation on the interval [0,2π)

2cos2θ = sinθ + 1

π, π/6, 3π/2

100

What type of Identity is this:

cscθ = 1/sinθ

Reciprocal Identity

100

Sine, cosine, and tangent are all positive in this quadrant.

Quadrant 1

200

sin(θ)csc(θ) - sin2(θ)

cos2(θ)

200

Verify the Trig Identity:

cosx(tan2x + 1) = sec(x)

cosx(tan2x + 1) 

cosx(sec2x)

cosx(1/cos2x)

1/cosx

sec(x)

200

Solve the equation over the interval [0,2π)

4sin2(3θ) - 3 = 0

π/9, 2π/9, 4π/9, 5π/9

200

What type of Identity is this:

sin2θ + cos2θ = 1

Pythagorean Identity

200

Simplify sin(π/6)

1/2

300

Simplify the Trig Expression:

(secθ/cscθ) + (sinθ/cosθ)

2tanθ

300

(1 - tan2x)/(1 + tan2x) = 1-2sin2x

(1 - tan2x)/(1 + tan2x) = 

(1 - tan2x)/(sec2x) = 

(1 / sec2x) - (tan2x/sec2x) = 

cos2x - sin2x = 

(1 - sin2x) - sin2x = 

1 - 2sin2x

300

Solve the equation and give the general solution:

4cosx = 1 + 2cosx

π/3 = 2πn, 5π/3 + 2πn

where n is an integer

300

What type of Identity is this:

tanθ = sinθ/cosθ

Ratio Identity

300

Simplify tan(2π/3)

√3

400

(sin4x - cos4x) / (sin2x - cos2x)

1

400

Verify the Trig Identity:

(sinx + cosx)2 + (sinx - cosx)2 = 2

(sinx + cosx)2 + (sinx - cosx)2

sin2x + 2cosxsinx + cos2x + sin2x - 2cosxsinx + cos2

2sin2x + 2cos2x

2(sin2x + cos2x)

2(1)

2

400

Solve the equation over the interval [0,2π)

3tan4x- 10tan2x = -3

π/6, 5π/6, 7π/6, 11π/6, π/3, 2π/3, 4π/3, 5π/3

400

What type of Identity are these:

cos(-θ) = cosθ & sin(-θ) = -sinθ

Even/Odd Formulas

400

The cosine of an angle is equal to √2/2 at these two angles.

Pi/4 and 7Pi/4 (45 and 315 degrees).

500

Simplify the Trig Expression:

sec(-x) + tan(-x)cos(𝝅/2 - x)

cos(x)

500

Verify the Trig Identity:

(1/(sinx - 1)) - (1/(sinx + 1)) = -2sec2

(1/(sinx - 1)) - (1/(sinx + 1)) =

(sinx + 1 - sinx + 1)/(sin2x -1) =

2/(-cos2x) = 

-2sec2x

500

Solve the equation and give the general solution:

2sin(3x) - √2 = 0

π/12 + (2πn)/3, π/4 + (2πn)/3

Where n is an integer

500

What type of Identity are these:

cos(π/2 - θ) = sinθ

Cofunction Identity

500

On the unit circle, you can find tangent this way.

What is divide y by x?