Trig 2.4 - Sum and Difference Formulas

Trig 2.4 - Sum and Difference Formulas

Warm up

Multiple Choice

1 - sin²x = _________?

• -cos²x

• sec²x

• cosx

• cos²x

Multiple Choice

• 1
• -1
• 0
• undefined

Multiple Choice

sin 7π/6

• 1/2
• -1/2
• √3/2
• -√3/2

Multiple Choice

cos(60°)

• 0
• 1/2
• √3/2
• 1

Multiple Choice

arccos(-1/2)

• π/3

• -5π/3

• 2π/3

• 2π/3 and 4π/3

Notes

2.4 Sum and Difference Formula

definitions

cosine example

Multiple Choice

Use Sum or Difference Identities to find the exact value of each expression.
cos(75°)

• 1/4
• ( √(6) - √(2) ) / 4
• (√(6) + √(2)) / 4
• (-√(6) - √(2)) / 4

Multiple Choice

sin 105º

• √3/2
• -1/4(√2 + √6)
• 1/4 (√2 + √6)
• 2-√3

Notes

2.4 Sum and Difference Formula

condense expressions

Multiple Choice

Find the exact value of the expression.

sin(5π/12)cos(π/4) - cos(5π/12)sin(π/4)

• 1/2

• -1/2

• -√(2)/2

• √(3)/2

Multiple Choice

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)

Notes

2.4 Sum and Difference Formula

tangent

Multiple Choice

Which of the following is equivalent to  $\tan\left(\alpha+\beta\right)$  ?

•  $\frac{\tan\alpha+\tan\beta}{1-\tan\alpha\tan\beta}$  

•  $\frac{\tan\alpha-\tan\beta}{1-\tan\alpha\tan\beta}$  

•  $\frac{\tan\alpha+\tan\beta}{1+\tan\alpha\tan\beta}$  

•  $\frac{\tan\alpha-\tan\beta}{1+\tan\alpha\tan\beta}$  

Multiple Choice

 $\tan105\degree$  

•  $2-\sqrt{3}$  

•  $2+\sqrt{3}$  

•  $-2-\sqrt{3}$  

•  $-2+\sqrt{3}$  

Poll

I understand the sum/difference formulas for sin/cos/tan

• 1 - not at all

• 2

• 3

• 4

• 5 - very confident

Homework 2.4