Question

A) The cosine rule can be used to find the value of x in the triangle below.

Answer 1

Answer:

see explanation

Step-by-step explanation:

(a)

(the side required )² = sum of squares of other 2 sides - ( 2 × product of other 2 sides and cos(angle opposite side required ) )

x² = 12² + 15² - (2 × 12 × 15 × cos71°)

(b)

x² = 144 + 225 - 360cos71°

   = 369 - 360cos71° ( take square root of both sides )

x = $\sqrt{369-360cos71}$

  ≈ 16 cm ( to the nearest integer )