Question

What is the value of BC in the given triangle?

Answer 1

1.2

Explanation:

Cosine rule: a ² = b ² + c ² - 2bc COS A

= 2² + 1² - 2(2)(1) cos 25

= 4 + 1 - 4 cos 25

= 5 - 4 cos 25

a = √(5 - 4cos 25)

= 1.17

= 1.2 (nearest to 1.17)