solution given;
let
AB=a
AC=b=30ft
AB=c=20ft
<A=115°
By using Cosine rule.
a²=b²+c²-2bc cos angle
a²=30²+20²-2*30*20 Cos 115°
a²=1807.1419
a=√[1807.1419]
a=42.51
Side A is 42.51ft.
Again
Cos B=[tex] \frac{a²+c²-b²}{2ac} [/tex]
Cos B=[tex] \frac{42.51²+20²-30²}{2*42.51*20} [/tex]
Cos B=0.7687
<B=Cos -¹(0.7687)
<B=39.46°
Angle B is 39.46°
