Question

Sinx-cosx=0 to sidh karo sin^4x cos^4x=0

Answer 1

Sinx - cosx = 0 

By squaring both the sides 

sin2x + cos2x - 2 sinx cosx = 0  ........ (1)

1 - 2 sinx cosx = 0 or 2 sinx cosx = 1 

again by squaring (1)

(sin2x + cos2x - 1)2  = (0)2

sin4x + cos4x + 1 + 2 sin2x cos2x - 2 cos2x - 2 sin2x = 0

sin4x + cos4x + 1 + 2(1) - 2 (1 - sin2x) -  2 sin2x = 0

sin4x + cos4x + 1 + 2 - 2 + 2 sin2x - 2 sin2x = 0 

sin4x + cos4x + 1 = 0 

sin4x + cos4x = -1

Hope it helps !!!

Answer 2

sinx - cosx=0
than
sinx = cosx
sinx = cosx *1
tanx = 1
than
x =1
now
= sin4x *cos4x
= cos(45*4 )*sin(45*4)
=cos 180 * sin180
=0