A.S.T.C
- Author:
- Ang Wee Kiat
Here you can explore how the sign of the trigonometrical ratios change when the angles are in different quadrants.
Remember the acronym "ASTC - All School Teachers Care! :)"
To find the sine, cosine and tangent values, we make use of the x and y coordinates (so that we can work with negative values)
We fix the hypotenuse to be 1 unit so that the calculation is less tedious.
so,
the sine ratio is y/1
the cosine ratio is x/1
the tangent ratio is y/x
-------------------------------------------------------------
Additional Exploration:
Consider the sine of the following angles:
sin 30 (first quadrant)
sin (180 - 30) = sin 150 (second quadrant)
sin (180 + 30) = sin 210 (third quadrant)
sin (360 - 30) = sin 330 (fourth quadrant)
What do you notice about the value, and sign of the resulting answers?
Is there a pattern for the cosine and tangent ratios as well? :)