Question

Cos A -24/25 dimana A dikuadran 3 . hitung nilai cos 2A ?

Answer 1

Verified answer

Trigonometri

cos A = -24/25 , negatif krn kuadran 3

x = 24
r = 25
y = √25² - 24² = 7

sin A = y/r
= 7/25
= -7/25 , negatif krn kuadran 3

cos 2A
= cos² A - sin² A
= (cos A + sin A)(cos A - sin A)
= (-24/25 + (-7/25))((-24/25) - (-7/25))
= (-31/25)(-17/25)
= 527/625