How do you solve #(sinx+cosx)/tanx+(1-sinx)/sinx=cosx# for #0<=x<=2pi#?

1 Answer
Feb 6, 2017

#{}#; no solution

Explanation:

Rewrite #tanx# as #sinx/cosx#:

#(sinx + cosx)/(sinx/cosx) + (1 - sinx)/sinx = cosx#

#(cosx(sinx + cosx))/sinx + (1 - sinx)/sinx = cosx#

#(cosxsinx + cos^2x + 1 - sinx)/sinx = cosx#

#cosxsinx + cos^2x + 1 - sinx = sinxcosx#

#cos^2x + 1 - sinx = sinxcosx- sinxcosx#

#cos^2x+ 1 - sinx = 0#

Use #sin^2x + cos^2x = 1#:

#1 - sin^2x + 1 - sinx = 0#

#0 =sin^2x + sinx - 2#

Factor:

#0 = (sinx + 2)(sinx - 1)#

#sinx = -2 and 1#

There is no solution to #sinx = -2#. However, #sinx = 1# is solvable.

#x = pi/2 #

However, this is extraneous, since #tan(pi/2)# is not defined in the real number system, aka:

#tan(pi/2) = sin(pi/2)/cos(pi/2) = 1/0 = "undefined"#

Therefore, this equation has no solution. This can be symbolized with an empty solution set #{}#.

Hopefully this helps!