# Chapter 11 - Section 11.4 - Applications with Acute Triangles - Exercises: 6a

$b^{2}$ = $(5.7)^{2}$ + $(8.2)^{2}$ - 2*5.7*8.2 cos 79°

#### Work Step by Step

Given data a=5.7,c=8.2, β=79° Using theorem 11.4.3 In triangle ABC $b^{2}$ = $a^{2}$ + $c^{2}$ - 2ac cos β $b^{2}$ = $(5.7)^{2}$ + $(8.2)^{2}$ - 2*5.7*8.2 cos 79°

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