It is that the angle has to be formed by two pairs of congruent/corresponding sides of the triangle
Derivitive of cosx=-sinx
dy/dx sinx=cosx
and use chain rue
2cosx=-2sinx
2cos2x=-4sin2x
so
-2sinx-4sin2x id the deritivitve
First can you change
2x + y = -12
To have y as the subject
Looks like y = ???
