165
= 180-15 or
= 120+45 or
= 90+75
I will pick 120+45
tan 165 = tan(120+45)
= (tan120 + tan 45)/(1 - tan120tan45) **
2
we know tan 45=1
tan120 = -tan60 , by the CAST rule
= -√3 , from the 30-60-90 triangle
so back in **
tan165 = (-√3 + 1)/(1 - (-√3)(1))
= (1 - √3)/(1 + √3)
Tan 165°
Use appropriate identity and evaluate
2 answers
Thank you