Question

( (b-c)^{2} cos ^{2} A / 2+(b+c)^{2} sin ^{2} A / 2 )
( Rightarrowleft[b^{2}+c^{2}-2 b cright] cos ^{2} A / 2+left[b^{2}+c^{2}+2 b cright] sin ^{2} A / 2 )
( Rightarrowleft[b^{2}+c^{2}right] cos ^{2} A / 2+2 b cleft[sin ^{2} A / 2^{-cos ^{2} A / 2}right] )
( =left[b^{2}+c^{2}right] cos ^{2} A_{2}+left[b^{2}+c^{2}right] sin ^{2} A_{2} )
( =b^{2}+c^{2}-2 b c cos A Rightarrow a^{2} )
triangle law

# 5-30 = = 25 = 3b = a - b - C = 36 Show that (b-c32006+(6+oʻsin = 2? = 62-2bc- Sol. LHS. = (-c) cos? --C) sin

Solution