How does the unit circle work for trigonometric ratios of obtuse angles? I know that the x coordinate is cos(θ) and the y coordinate is sin(θ). But I understand these in context of only acute angles? I don't understand why the unit circle definition works for other than acute angles? Somebody please provide me some good intuition.
Asked
Active
Viewed 245 times
1
-
You may find this answer of mine helpful. – Blue Nov 09 '17 at 09:45
-
4Possible duplicate of How does the unit circle work for trigonometric ratios of non-acute angles? -- in fact the wording of the question is exactly the same. – David K Jul 16 '19 at 00:31
1 Answers
1
Take the ratios $x/r$ and $y/r$ as the defintions of cosine and sine. Note that the definitions you already know for acute angles (“opposite side/hypotenuse” etc) then become a special case.
Mathemagical
- 3,489
-
1I would prefer this to be reintroduced as defintions in high school for all angles when students get to coordinate geometry. – Mathemagical Nov 09 '17 at 08:05