Answer:
110.9° = 111°
Step-by-step explanation:
Given ∆ABC, where
length of side AB = 15 cm,
length of side AC = 7 cm
length of side BC = 11 cm
Required:
Size of largest angle in ∆ABC
SOLUTION:
The size of the largest angle in the triangle is the angle that has the largest side length opposite it.
Therefore, the largest angle in ∆ABC = <C, which has a side length of 15 cm opposite it.
=>Find the angle of C using the Law of Cosine
Cos C = (a² + b² - c²)/2ab
Cos C = (11² + 7² - 15²)/2*11*7
Cos C = (121 + 49 - 225)/154
Cos C = -55/154
Cos C = -0.3571
C = Cos-¹(-0.3571)
C = 110.9° ≈ 111°
