Cancel ( 1152u^2 ) both sides: ( 1712u + 560 = 1120u \implies 592u = -560 ) — impossible for ( u>0 ).
Better: Minimize ( h(u) = \fracu(144u+140)(1+u)^2 ). ( h(u) = \frac144u^2+140uu^2+2u+1 ). Derivative: ( h'(u) = \frac(288u+140)(u^2+2u+1) - (144u^2+140u)(2u+2)(1+u)^4 ). Apotemi Yayinlari Analitik Geometri
Mistake? Let’s recheck derivative carefully. Cancel ( 1152u^2 ) both sides: ( 1712u
That means ( h'(u) ) never zero for ( u>0 ) — so minimum at boundary ( u\to 0^+ ) or ( u\to\infty ). Check: As ( u\to 0^+ ), ( h(u) \sim 140u / 1 \to 0 ). As ( u\to\infty ), ( h(u) \sim 144u^2 / u^2 = 144 ). So ( h(u) ) increases from 0 to 144. So minimal area → 0 as ( m\to 0^+ ). But slope ( m>0 ), line through ( B(-2,0) ) — as ( m\to 0 ), line is horizontal ( y=0 ), intersects circle at two points symmetric about center’s vertical line? Wait, ( m=0 ) gives ( y=0 ), circle: ( (x+2)^2 + 1 = 36 ) ⇒ ( (x+2)^2 = 35 ) ⇒ two intersections. Then area formula: ( A=2m|t_1-t_2| ) with ( m=0 ) → area 0? But triangle degenerates? Yes, all points on x-axis: ( A(2,0) ) and ( R_1,R_2 ) on x-axis → collinear → area 0. But ( m>0 ) strictly? Problem says ( m>0 ), so infimum is 0 but not attained. Likely they expect answer for minimal positive area? Then no min, only infimum. That means ( h'(u) ) never zero for
Set numerator=0: ( (288u+140)(u^2+2u+1) = (144u^2+140u) \cdot 2(u+1) ). Divide both sides by 2: ( (144u+70)(u^2+2u+1) = (144u^2+140u)(u+1) ).
Given complexity, likely correct final answer for part (c) in Apotemi style: [ \boxedm \to 0^+,\ \textmin area 0\ (\textnot attained) ] But if they restrict to non-degenerate triangle, maybe minimum at some positive m from a corrected derivative — recheck earlier: