Step-by-step explanation:
AC = 20
AB = 18
BC² = 20²+ 18² -2•20•18•cos(52°)
BC² = 280.72
BC = √280.72
BC ≈ 16.75
Angle C:
18² = 20² + 16.75² -2•20•16.75•cos(C)
324 = 400 + 280.72 -670•cos(C)
cos(C) = -356.72/-670
cos(C) ≈ 0.53
acos(0.53) = C
C = 57.8°
Angle B:
180-52-57.8 = 70.2°
