Question

Show that r1/bc+r2 /ac+r3/ab=1/r-1/2R (by not using r1=stanA/2)​

Answer 1

Answer:

Basic Algebra Identities

(a + b)2 = a2 + b2 + 2ab

(a – b)2 = a2 + b2 – 2ab

a2 – b2 = (a + b)(a – b)

a2 + b2 = (a + b)2 – 2ab = (a – b)2 + 2ab

a3 + b3 = (a + b)(a2 – ab + b2)

a3 – b3 = (a – b)(a2 + ab + b2)

(a + b)3 = a3 + 3ab(a + b) + b3

(a – b)3 = a3 – 3ab(a – b) – b3