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_A_ {(s—b)(s—c) dos! = s(s — a), oe Be and cos > = be, _B (s —c)(s—a) B s(s—b), sin>== |——————_ and cos= =, , 2 ca 2 ca, , yo, , .C_ |(s—aj(s—b) a C_ |s(s—c), sing = ab and cos = a, ti _ {@-b)G-0) A_(s—b)(s—c), = s(s—a) a A, , B_ |(s—c)(s—a) B_(s—c)(s—a), ‘ana | 16-5) © tanz = a, i Cc S-a)(s~- 5), Cc (s—a)(s—b), aie a s(s—c) e 2 A, fi B-C_ b-c A ag pt A= @), ND ten PO ER, t C-A_c-a 22 eo 22 s6—b), nD tan PO ER, 4 A-B_a-b f “% -£ SIS =¢), aD apy OD, , _A _ A . _ A : _, peg aye sop, , , , Where r denotes the radius of the in — circle, and r,,T2,13 denotes the radii of ex — circles.