lalu cari sudutnya
α = arctan (y/x)
α = arctan (-√3/1)
α = arctan (-√3)
α = 120°
x = r . Cos α
x = 6 . cos 240°
x = 6 . -1/2
x = -3
y = r . Sin α
y = 6 . sin 240°
y = 6 . -1/2 √3
y = -3√3
DF = 12 cm
DE = 8 cm
sin D = sin 120° = 1/2 √3
Luas segitiga
= 1/2 x DF x DE x sin D
= 1/2 x 12 cm x 8 cm x sin 120°
= 6 cm x 8 cm x 1/2 √3
" Life is not a problem to be solved but a reality to be experienced! "
© Copyright 2013 - 2024 KUDO.TIPS - All rights reserved.
9. Konversi titik P(-1, √3) ke bentuk koordinat kutub
Pembahasan:
lalu cari sudutnya
α = arctan (y/x)
α = arctan (-√3/1)
α = arctan (-√3)
α = 120°
Jadi titik kutubnya (r,α) adalah (2, 120°) B
10. Konversi titik kutub (6, 240°)
Pembahasan:
x = r . Cos α
x = 6 . cos 240°
x = 6 . -1/2
x = -3
y = r . Sin α
y = 6 . sin 240°
y = 6 . -1/2 √3
y = -3√3
jadi titik koordinat cartesiusnya adalah C (-3, -3√3)
16. Diketahui:
DF = 12 cm
DE = 8 cm
sin D = sin 120° = 1/2 √3
Pembahasan:
Luas segitiga
= 1/2 x DF x DE x sin D
= 1/2 x 12 cm x 8 cm x sin 120°
= 6 cm x 8 cm x 1/2 √3
= 24√3 cm (E)