Jawab:
(1a.)  x = 30°, y = 44√3
(1b.)  x = 15°, y = 12√2
(1c.)  x = 45°, y = 100

Penjelasan:
(1a.) cari x
180° = 30° + 120° + x
180° = 150° + x
x = 180° - 150°
x = 30°
cari y pake hukum sinus
y/(sin120°) = 44/(sin30°)
y/(sin(180°-120°)) = 44/(½)
y/(sin60°) = 44(2)
y/(½√3) = 88
y = 88(½√3)
y = 44√3
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(1b.) cari x
180° = x + 30° + (180°-45°)
0 = x + 30° - 45°
x = 45° - 30°
x = 15°
cari y pake hukum sinus
y/(sin30°) = 24/(sin(180°-45°))
y/(sin30°) = 24/(sin45°)
y/(½) = 24/(½√2)
½√2 y = ½(24)
√2 y = 24
y = 24/√2
y = 24√2/2
y = 12√2
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(1c.) Cari x pakai hukum cos
FPB dari 100, 125, 175 adalah 25
sisi-sisi sebangun
a                   c             b
(100√2/25), (125/25), (175/25)
4√2,             5,            7
maka a = 4√2, b = 7, c = 5
Dengan hukum cos
c² = a² + b² - (2ab · cos(x))
5² = (4√2)² + 7² - (2(4√2)(7)cos(x))
25 = 4²(√2)² + 49 - 56√2 cos(x)
25 = 16(2) + 49 - 56√2 cos(x)
25 = 32 + 49 - 56√2 cos(x)
56√2 cos(x) = 32 + 49 - 25
56√2 cos(x) = 56
√2 cos(x) = 1
cos(x) = 1/√2
x = cos⁻¹ 1/√2
x = 45°
Cari y dengan perbandingan sisi
y = depan, 100√2 = miring
sin x = depan/miring
sin 45° = y/100√2
1/√2 = y/100√2
y = 100

(xcvi)