Tangent Lines & Circles

Front

What is a tangent line?

Back

A tangent line is a straight line that touches a circle at exactly one point, known as the point of tangency.

Front

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

Back

A tangent to a circle is perpendicular to the radius drawn to the point of tangency.

Front

If two tangent lines are drawn from the same external point, what can be said about their lengths?

Back

The two tangent lines are congruent.

Front

What is the measure of a tangent line if it is 10 units long?

Back

The length of the tangent line is 10 units.

Front

Solve for x: A tangent line to a circle is 20 units long. What is x?

Back

x = 20.

Front

What is the definition of a circle?

Back

A circle is a set of points in a plane that are equidistant from a fixed point called the center.

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

If a radius measures 5 units, what is the diameter of the circle?

Back

The diameter d is 10 units, since d = 2r.

Front

What is the term for the point where a tangent line touches a circle?

Back

The point of tangency.