Answer:
AB = 10.2m
Step-by-step explanation:
Area of triangle ADC = 52m²
AD = 12m, angle D = 102°
Area of triangle ADC = ½ × a × b × sinC
52m² = ½ × 12 × CD × sin102
52 = 6 × CD × 0.9781
CD = 52/(6× 0.9781)
CD = 52/(5.8686)
CD = 8.86m = 8.9m (1 decimal place)
Using Cosine rule to find AC = d
d² = a² + c² -2×a×d ×cosD
d² = 8.9² + 12² - 2×8.9×12× Cos102
Cos102 = -0.2079
d² = 267.61744
d = √(267.61744)
AC = d = 16.4m
For ∆ABC
Using sine rule:
a/sinA = b/sinB
AB/sin46 = AC/sin120
AB/0.7193 = 16.4/0.866
AB = 14.2024 ×0.7193
AB = 10.2m (1 decimal place)
