is cotx-1=cosx-sinx

Answer 1

cotx -1 = cosx -sinx

cosx/sinx - 1 = cosx - sinx

multiply by sinx

cosx - sinx = (cosx -sinx)sinx

divide by cosx-sinx

1 = sinx

x = pi/2 or pi/2 + 2npi where n= any integer

cotx -1 = cosx -sinx when x = 90 degrees or 90+n360 where n = any integer