ABC is a triangle
The angle A = 30 degrees
AB = 7cm
BC = 5 cm
C is an acute angle. Find the size of angle C?
I need to use the cosine rule here Cos C = (a^2 + b^2 - c^2) / 2ac
The Attempt at a Solution
The problem is I do not know the size of side b?
So how can I attempt to resolve the answer?
Cos C = (5^2 + b^2 - 7^2) / 2*5*7