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AP EAMCET · Maths · Properties of Triangles

What is the greatest angle of the triangle whose sides are \(x^2+x+1,2 x+1, x^2-1\) ?

  1. A \(A=120^{\circ}\)
  2. B \(A=90^{\circ}\)
  3. C \(A=135^{\circ}\)
  4. D \(A=60^{\circ}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(A=120^{\circ}\)

Step-by-step Solution

Detailed explanation

Sides of triangle are \(\begin{aligned} & x^2+x+1,2 x+1 \text { and } x^2-1 \\ & x^2+x+1 \text { is the greatest side. }\end{aligned}\) \(\therefore \cos A=\frac{b^2+c^2-a^2}{2 b c}\) Here, \(a=x^2+x+1, b=2 x+1, c=x^2-1\)…