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TS EAMCET · Maths · Properties of Triangles

In a triangle, if the length of the sides a, b and c are three consecutive natural numbers and a<b<c, then cosA+cosB+cosC2abc=

  1. A 3bb2-2
  2. B 3b3+6b2+3b
  3. C 3 b+23 b-2 b
  4. D b-1 bb+1
Verified Solution

Answer & Solution

Correct Answer

(A) 3bb2-2

Step-by-step Solution

Detailed explanation

(cosA+cosB+cosC)2abc =b2+c2-a22bc+a2+c2-b22ac+a2+b2-c22ab2abc =a(b2+c2-a2)+ba2+c2-b2+ca2+b2-c22abc2abc =a(b2+c2-a2)+ba2+c2-b2+ca2+b2-c2 Put a=b-1 & c=b+1 as a,b,c are three consecutive natural numbers & a<b<c.…