Use a half-angle identity to find the exact value of tan 165 degrees

- 2

Step-by-step explanation:

Using the half- angle identity

tan( ) =

= 165° ⇒ x = 330°

sin330° = - sin30° = -

cos330° = cos30° =

tan165° =

            =

            = - ×

            = -

Rationalise by multiplying numerator/ denominator by the conjugate of the denominator

The conjugate of 2 + is 2 - , hence

tan 165°

= -

= -

= - (2 - )

= - 2 + = - 2

29933333.33

step-by-step explanation:

x² + 11x + 18 < 0  

[-11 ± sqrt(121 - 72)]/2 = (-11 ± 7)/2  

solution: (-9, -2)

step-by-step explanation: