use the identity
so,
set it to zero
this factors
from this you will get
do you understand the answers from the quadradric
now one thing I don't really understand is why is it that some of these questions only have 1 answers while some have more than 5!
I know you have to look at which quadrant they are in and the range, is that true? for eg. in the 2nd quad, you have to take 180deg + 'basic angle'. I'm not really clear on this.
ok starting from the factored quadradic which is
if you take so that it becomes zero the whole equation goes to zero so if then that will be some our answer
so or so is only 1 at that is only place on the interval that it can
we do the same with except the results will show up in 2 places on the interval
can you see this....
sorry i am slow on this not real fast with the latex
I will help you more if you need.
interval is
is within we are not concerned about what quadrant it is in.
using substitution where
you have
which is factored as
it is easier to use rather than since we can then recognise the commonly known
so so substituting it back into the factors we can solve
see the chart below(which i stole from another thread to see how these were derived..
are we getting the picture???
ok, again, it will be easier to replace
with the identity
then we can work with
multiply both sides by to get
now divide both sides by to get
this has 2 answers and
they are in the III and IV quadrants respectfully
do you still need help with the next one you originally posted