CBSE

MATHEMATICS · Single correct · CBSE · Mathematics · Trigonometric Functions · Trigonometric Functions

Problem

In any

\triangle ABC

,

2[bc\cos A+ca\cos B+ab\cos C]=

(1)

a^2+b^2+c^2

(2)

a^2+b^2-c^2

(3)

a^2-b^2+c^2

(4) None of these

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