In ∆ ABC, ∠ A is the largest angle and ∠ B is

Solution

According to the question, ∠ A = 2∠ B and the length of the sides of the triangle are consecutive positive integers. So, a = x + 1 c = x b = x - 1 Now, by using the sine rule.   (sin 2B)/ (x + 1) = (sin B)/ (x - 1)   (sin 2B)/ (x + 1) =sinB/ (x-1) 2sinBcosB/ x + 1 = (sin B)/ (x - 1) 2cosB= (x + 1)/ (x - 1)                     … (1) Now, by using the cosine rule, cosB= (a²+c²-b²)/2ac On substituting the value of the respective variable in the above formula, we get, cosB=(x+1)² +x²-(x-1)²/ 2(x+1) x cosB=(x²+1+2x+x²-x²-1+2x)/ 2x²+2x cosB=(4+x)/2(x+1)                            … (2)   On equating (1) and (2), we get, (4+x)/(x+1) =(x+1)/(x-1) = 4x-4 + x² - x = x² + 1 + 2x x=5 units The length of the largest side, x+1=5+1 =6 units