asked 87.1k views
0 votes
How do you find the sine, cosine, and tangent values on the unit circle not in the first quadrant? Provide an example, and how you would find the sine, cosine, and tangent of the value you chose

asked
User Matroska
by
8.6k points

1 Answer

4 votes
A point (-0.8, 0.6) will be a point on the unit circle in the second quadrant. Since it is a unit circle, its radius is 1, and we have
sin(α) = y = 0.6
cos(α) = x = -0.8
tan(α) = y/x = 0.6/-0.8 = -0.75

The angle is α = arccos(-0.8) ≈ 143.13°

______
For the unit circle, the trig values are always the coordinates or their ratio as shown above, regardless of quadrant.
answered
User Evren
by
7.8k points
Welcome to Qamnty — a place to ask, share, and grow together. Join our community and get real answers from real people.