Question

Bethany used the steps below in an attempt to solve for angle B in triangle ABC.

Answer 1

Given that,

The area parameters are

A = 2.7 cm, B = 4.1 cm C = 4.5 cm

We want to find the angle extended by B.

Using cosine Rule

b² = a² + c² - 2ac•Cosθ

4.1² = 2.7² + 4.5² - 2 × 2.7 × 4.5• Cosθ

16.81 = 7.29 + 20.25 - 24.3•Cosθ

16.81 - 7.29 - 20.25 = -24.3•Cosθ

-10.73 = -24.3•Cosθ

Cosθ = -10.73 / -24.3

Cosθ = 0.4416

θ = Cos~1 (0.4416)

θ = 63.8°

The angle B is 63.8°