Sal constructs a circle that circumscribes a given triangle using compass and straightedge. Created by Sal Khan.

Unit circle introduction Learn Unit circle The trig functions & right triangle trig ratios

You can know if a bound can be equal to x by looking to see if the circle representing the bound on the graph is filled in or not. A filled in circle means it can be equal to x, and open circle means it cannot …

So point A is on a circle. If you were to rotate point A, it would still be on the circle. The rotation angle is -120 degrees. Since it is negative, the direction the point rotates in is clockwise. Point A is currently at …

Learn the relationship between the radius, diameter, and circumference of a circle.

Standard equation of a circle Learn Features of a circle from its standard equation Graphing a circle from its standard equation

Features of a circle from its expanded equation Google Classroom You might need: Calculator

Remember, the circle itself is all of the points that are equal distance from the center. So AB, any line segment, I should say, that connects the center to a point on the circle, we would call a radius.

We have it in the standard form of a circle. You remember that if a circle is centered at 0, the standard form would be x squared plus y squared is equal to r squared.

With the unit circle and the Pythagorean theorem, we can find the exact sine, cosine, and tangent of the angles π/6 and π/3. Created by Sal Khan.