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AP EAMCET · Maths · Properties of Triangles

In \(\triangle A B C, \frac{1}{r_1^2}+\frac{1}{r_2^2}+\frac{1}{r_3^2}+\frac{1}{r^2}=\)

  1. A \(\frac{a^2+b^2+c^2}{\Delta^2}\)
  2. B \(\frac{a+b+c}{\Delta^2}\)
  3. C \(\frac{s^2}{\Delta^2}\)
  4. D \(\frac{4 s^2}{\Delta^2}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(\frac{a^2+b^2+c^2}{\Delta^2}\)

Step-by-step Solution

Detailed explanation

\(\because\)\(r_1=\frac{\Delta}{s-a}\) \(\therefore\) \(\frac{1}{r_1}=\frac{s-a}{\Delta}\) Similarly, \(\frac{1}{r_2}=\frac{s-b}{\Delta} \frac{1}{r_3}=\frac{s-c}{\Delta}\) and \(\frac{1}{r}=\frac{s}{\Delta}\) Now, \(\frac{1}{r_1^2}+\frac{1}{r_2^2}+\frac{1}{r_3^2}+\frac{1}{r^2}\)…