Question

Please solve this trigo,one step left..

Answer 1

(cosX-cosY)^2+(sinX-sinY)^2=4sin^2X-Y/2
Prove..

Answer 2

osx-cosy= -2sin(x+y)/2. sin(x-y)/2 -----(1)
sinx-siny= 2 cos(x+y)/2 .sin(x-y)/2-----(2)
Therefore
(cosx-cosy)2+ (sinx-siny)2= 4sin2(x+y)/2 .sin2(x-y)/2 + 4cos2(x+y)/2.sin2(x-y)/2
= 4sin2(x-y)/2 {sin2(x+y)/2 + cos2(x+y)/2} =4sin2 (x-y)/2*1= 4sin2(x-y)/2 = RHs hence proved

Answer 3

ive done this much
http://gyazo.com/12a66197150777ca69f1e3d178ef88b8

Answer 4

osx-cosy= -2sin(x+y)/2. sin(x-y)/2 -----(1)
sinx-siny= 2 cos(x+y)/2 .sin(x-y)/2-----(2)
Therefore
(cosx-cosy)2+ (sinx-siny)2= 4sin2(x+y)/2 .sin2(x-y)/2 + 4cos2(x+y)/2.sin2(x-y)/2
= 4sin2(x-y)/2 {sin2(x+y)/2 + cos2(x+y)/2} =4sin2 (x-y)/2*1= 4sin2(x-y)/2 = RHs hence proved

Answer 5

my method is easyy