Question 1203484
<pre>

{{{cos^""(x)-3sin^""(x)}}}{{{""=""}}}{{{3}}}

{{{cos^""(x) }}}{{{""=""}}}{{{ 3sin^""(x)+3}}}

{{{cos^""(x) }}}{{{""=""}}}{{{ 3(sin^""(x)^""+1)}}}

Square both sides:

{{{cos^2(x)}}}{{{""=""}}}{{{9(sin^2(x)+2sin^""(x)^""+1)}}}

{{{1-sin^2(x)}}}{{{""=""}}}{{{9sin^2(x)+18sin^""(x)+9)}}}

{{{0}}}{{{""=""}}}{{{10sin^2(x)+18sin^""(x)+8}}}

{{{10sin^2(x)+18sin^""(x)+8}}}{{{""=""}}}{{{0}}}

{{{5sin^2(x)+9sin^""(x)+4}}}{{{""=""}}}{{{0}}}

{{{(sin^""(x)^""+1)(5sin^""(x)^""+4)}}}{{{""=""}}}{{{0}}}

{{{matrix(3,3,
sin^""(x)+1=0,"",  5sin^""(x)+4=0,
  sin^""(x)=-1,"",    5sin^""(x)=-4,
        "",    "",    sin^""(x)=-4/5)}}}

Were you asked to solve in degrees or radians?
Were you asked to find all solutions? Or just the smallest positive solutions?

Since we don't have answers to these questions, we can go no further.  So you
must finish.  Be sure to check for extraneous answers since we squared both
sides, which very often introduces extraneous answers we must discard. But this
is not necessarily the case.

Edwin</pre>