Mistake Master
Mistake Master · AP Precalculus · Unit 3 · Step-Through Animation
One Point Carries All Three Values
You'll learnto read cosine, sine, and tangent off one point on the unit circle.
An angle, a circle of radius 1, and the single point where the terminal ray crosses it. Cosine is that point’s x, sine is its y, and tangent is the ray’s slope. Watch the point move, watch the three values move with it, and watch a calculator in the wrong mode answer a completely different question.
cosine rides first
Before you start
What you're looking at
A still unit circle labeled with the angle, the terminal ray, and the point (x, y) where the ray crosses.
The question
Which value is the point's x, which is its y, and which is the ray's slope?
Watch for
Cosine is x, sine is y, tangent is slope — revealed one at a time, with calculator mode saved for a final warning.
Step 1 / 8