hello, i am trying to evaluate a trig ratio but the example is quite hard to follow. can someone please explain how this question is done,
given that and that
hence without calculators evaluate and
All you got here is to substitute the values. I think you can do that. For the second part, what you should know is that and
A more detailed discription about trignometric identities could be found at, List of trigonometric identities - Wikipedia, the free encyclopedia
Hope this helps.
Since x falls in the second quadrant , sin is positive and cos is negative
Draw a triangle with sides labelled according to the trigo ratio , and use phythagoras theorem to evaluate the other side .
in this case , hypothenus=13 , opposite side =12, adjacent=5
cos x=adjacent/hypothenus=5/13 but look at red , so cos x=-5/13
for the remaining examples ,just expand and substitute appropriately .