Calculate the size of the largest angle in the triangle. Give your answer to an appropriate degree of accuracy.

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°

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step-by-step explanation: