No 16 kak tolong bantu

Nilai trigonometri

cos β = - ¹/₂√3 dan β dikuadran II
cos β = -¹/₂ √3 = - cos 30 = cos (180-30) = cos 150
β = 150
tan 150= tan (180 - 30) = - tan 30 = - 1/√3 =  -¹/₃ √3