Inverse Circular Functions 3 Question 11

11. If a,b,c are positive real numbers θ=tan1a(a+b+c)bc+tan1b(a+b+c)ca

+tan1c(a+b+c)ab

Then, tanθ equals

(1981, 2M)

Show Answer

Answer:

Correct Answer: 11. 0

Solution:

  1. Given,

θ=tan1a(a+b+c)bc+tan1b(a+b+c)ac+tan1c(a+b+c)abtan1x+tan1y+tan1z=tan1x+y+zxyz1xyyzzx

=tan1(a+b+c)a+b+cabc1(a+b+c)1a+1b+1c

=tan1a+b+cabc(a+b+c)(a+b+c)a+b+cabc1(a+b+c)(ab+bc+ca)abcθ=tan10tanθ=0



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