Question

Nilai x yang memenuhi persamaan
Cos (5/2x) + sin 30° = 0 , jika 90° ≤ x ≤ 270°
Plis fast respon dan pke caranya yaa

Answer 1

Verified answer

Persamaan Trigonometri

cos (5/2)x + sin 30 = 0
Untuk 90 ≤ x ≤ 270

cos (5/2)x + 1/2 = 0
cos (5/2)x = -1/2
Karena negatif , ia pasti berada di kuadran 2 sampai 3 saja.

Rumus Kuadran II
cos (180 - a) = - cos a
cos (180 - a ) = -1/2
cos (180 - a) = - cos 60
cos 120 = - cos 60

cos (5/2)x = cos 120
x = 120 . 2/5
x = 48°
Tidak Memenuhi

Rumus Kuadran III

cos (180 + a) = - cos a --> -1/2
cos (180 + a) = - cos 60
cos (180 + 60)
= 240°

(5/2)x = 240
x = 240 . 2/5
x = 96°

memenuhi utk 90° ≤ x≤ 270°

Hp = { 96° }