Answer:
Option D
Step-by-step explanation:
By applying cosine rule in the given triangle,
a² = b² + c² - 2b.c.cos(m∠A)
By substituting values in the formula,
9² = 10² + c² - 2(10)(c)cos(15)°
81 = 100 + c² - 19.32c
c² - 19.31c + 19 = 0
By quadratic formula,
c = [tex]\frac{19.31\pm\sqrt{(19.31)^{2}-4(1)(19)}}{2(1)}[/tex]
= [tex]\frac{19.31\pm17.23}{2}[/tex]
= 1.08, 18.27
≈ 1.1, 18.3
Therefore, Option D will be the answer.
