Question

Find the length of a. Round to 3 decimals.

Answer 1

a ≈ 22.184

Explanation:

Using the Cosine rule in Δ ABC

a² = b² + c² - 2bc cosA

Here b = 15, c = 12 and A = 110° , then

a² = 15² + 12² - (2 × 15 × 12 × cos110° )

= 225 + 144 - 360 cos110°

= 369 - 360 cos110°

= 492.12725.. ( take the square root of both sides )

a =
`√(x492.12725)` ≈ 22.184 ( to 3 dec. places )