Engineering
Mathematics
Basic Rules of Properties of Triangle
Question

If the angles A, B and C of a triangle are in an arithmetic progression and if a, b and c denote the lengths of the sides opposite to A, B and C respectively, then the value of the expression acsin2C+casin2A , is

 32

 12

1

 3

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Solution

= 2 sin(A + C) = 2 sin (π – B) = 2 sin B

 As A + B + C = π    and   A + C = 2B                B = 60°

          E = 2 sin 60° =  2(32)=3  Ans.

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