Unit Circle (Degrees)

sin 150

• -1/2
• -√3/2
• 1/2
• √3/2

cos 90

• 0
• 1
• -1
• undefined

tan 270

• 0
• 1
• -1
• undefined

tan 225

• √2/2
• -√2/2
• 1
• -1

cos 135

• √2/2
• -√2/2
• √3/2
• -√3/2

tan 210

• √3
• -√3
• √3/3
• -√3/3

We use the Unit Circle to construct the sine and the cosine functions. The unit circle is called the unit circle because:

• It is only one circle

• The area of the circle is equal to one

• Because its radius is equal to one

• Because its circumference is equal to one

sin 210°

cos 135°

• √2/2

• -√2/2

• √3/2

• -√3/2

cos(60°)

• 0
• 1/2
• √3/2
• 1