- #1

- 493

- 8

## Homework Statement

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?

## Homework Equations

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