Tangent, Secant and Chord Circle Theorems

Front

What is a chord in a circle?

Back

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

Front

What does it mean for a diameter to be perpendicular to a chord?

Back

It means that the diameter intersects the chord at a right angle, bisecting the chord.

Front

What is the Pythagorean Theorem?

Back

In a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the other two sides.

Front

What is the angle measure of a semicircle?

Back

180 degrees.

Front

What is a secant line?

Back

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

Front

What is a tangent line?

Back

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

Front

What is the relationship between tangents drawn from a point outside a circle?

Back

Tangents drawn from a point outside a circle are equal in length.

Front

What is the Inscribed Angle Theorem?

Back

The measure of an inscribed angle is half the measure of the intercepted arc.

Front

What is the relationship between angles formed by intersecting chords?

Back

The measure of the angle formed by two intersecting chords is equal to the average of the measures of the arcs intercepted by the angle and its vertical angle.

Front

How do you find the length of a chord given its distance from the center?

Back

Use the Pythagorean Theorem: if d is the distance from the center to the chord and c is half the length of the chord, then r^2 = d^2 + c^2, where r is the radius.