Question

What is the length of BC?please help!!!

Answer 1

2.1

Explanation:

using cosine theorem or substraction of two vector

b = AC = 5

c = AB = 6

a² = b² + c² - 2bc cos A

a² = 5² + 6² - 2*5*6 cos 20°

a² = 4.62

a = √4.62

a = 2.149

a ≈ 2.1