jika cos x =2/3, 270°
Matematika
magda2001
Pertanyaan
jika cos x =2/3, 270°<x<360° brp cot x?
1 Jawaban
-
1. Jawaban whongaliem
270° < x < 360° ⇒ x di kuadran III dan cot x bernilai - (negatif)
tan² x + 1 = 1/cos² x
tan² x + 1 = 1/(2/3)²
tan² x + 1 = 1/(4/9)
tan² x + 1 = 9/4
tan² x = (9/4) - 1
tan² x = 5/4
tan x = √(5/4)
tan x = ( - √5) / 2 atau tan x = (√5) / 2 (tak memenuhi)
cot x = 1/tan x
= 1 /( - √5 / 2)
= - 2 /√5
= - (2/5)√5