Circles and Tangent Lines

Front

What is a tangent line to a circle?

Back

A tangent line is a straight line that touches a circle at exactly one point.

Front

What is the relationship between a tangent line and the radius at the point of tangency?

Back

The tangent line is perpendicular to the radius drawn to the point of tangency.

Front

What is a chord in a circle?

Back

A chord is a line segment whose endpoints both lie on the circle.

Front

What is the definition of a secant line?

Back

A secant line is a line that intersects a circle at two points.

Front

If two tangent segments are drawn from a point outside a circle, what can be said about their lengths?

Back

The lengths of the two tangent segments are equal.

Front

What is the formula for the circumference of a circle?

Back

The circumference C of a circle is given by the formula C = 2πr, where r is the radius.

Front

What is the formula for the area of a circle?

Back

The area A of a circle is given by the formula A = πr², where r is the radius.

Front

How do you find the radius of a circle if you know the length of a tangent segment?

Back

The radius can be found using the Pythagorean theorem if the length of the tangent segment and the distance from the center to the point of tangency are known.

Front

What is the relationship between the diameter and the radius of a circle?

Back

The diameter is twice the length of the radius (d = 2r).

Front

What is the central angle of a circle?

Back

A central angle is an angle whose vertex is at the center of the circle and whose sides intersect the circle.