Angle A is in standard position with its terminal arm in quadrant III, the Trigonometry ratio sinA=-3/7 is given, how do you find the values of the other ratios?
There are, broadly speaking, two approaches.
No pictures or thinking about pictures (or not much)
We are given:
This tells us that:
Now the fact that A has terminal side in Q III tells us the
Now that we have
Method 2, thinking about the definitions of the trigonometric ratios:
There are several possible approaches to this:
And the fact that we are in Q III, to get
for points on the terminal side
We can choose one of these points (the unit circle approaches chooses
In Q III, we must have