1.

In any ΔABC, prove that (c2 – a2 + b2) tan A = (a2 – b2 + c2) tan B = (b2 – c2 + a2) tan C

Answer»

To prove

(c2 – a2 + b2) tan A = (a2 – b2 + c2) tan B = (b2 – c2 + a2) tan C

We know

tan A = \(\frac{abc}R\)\(\frac{1}{b^2+c^2-a^2}\).......(a)

Similarity, tan B = \(\frac{abc}R\)\(\frac{1}{b^2+c^2-a^2}\) and tanC = \(\frac{abc}R\)\(\frac{1}{b^2+c^2-a^2}\)

Therefore,

(c2 - a2 + b2) tanA = (a2 - b2 + c2) tanB = (b2 - c2 +a2) tanc = \(\frac{abc}R\)

Hence we can conclude comparing above equations.

(c2 – a2 + b2) tanA = (a2 – b2 + c2) tanB = (b2 – c2 + a2) tanC 

[Proved]



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