Theorems with Chords & Tangents Flashcards

All 7 cards in this deck

What is a chord of a circle?

A straight line joining two points on the circumference.

What is the difference between a sector and a segment of a circle?

A sector is bounded by two radii and an arc; a segment is bounded by a chord and an arc.

What is the angle between a tangent and the radius at the point of contact?

$90^\circ$ — the tangent to a circle is perpendicular to the radius.

What is the equal-tangents property?

The two tangents drawn to a circle from the same external point are equal in length.

What does the perpendicular from the centre of a circle to a chord do?

It bisects the chord (cuts it into two equal halves).

True or false? The angle between a tangent and a chord at the point of contact is always $90^\circ$.

False. It is $90^\circ$ only between a tangent and the radius (or diameter) at that point.

True or false? A triangle formed by two radii and a chord of a circle is always isosceles.

True. The two radii are equal in length, so the base angles at the ends of the chord are equal.