options: Construct the inscribed and circumscribed circles of a triangle, and prove properties of angles for a quadrilateral inscribed in a circle.

Identify and describe relationships among inscribed angles, radii, and chords. Include the relationship between central, inscribed, and circumscribed angles; inscribed angles on a diameter are right angles; the radius of a circle is perpendicular to the tangent where the radius intersects the circle.

Construct a tangent line from a point outside a given circle to the circle.

Prove that all circles are similar.
problem_activity: Problem 1
Based on the definition of each feature of a circle below, label the circle with the appropriate vocabulary words.
Arc:
Part of any curve
Central angle:
An angle formed by two radii with the vertex as the center of the circle
Chord:
A line segment containing two points on a curve
Diameter:
A line segment connecting two points on a curve that passes through the center of the circle
Radius:
A line segment that connects the center of a circle and a point on the circle
Tangent:
A line that intersect a circle at one and only one point
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Problem 2
Below is circle
$$A$$
with points
$$E$$
,
$$C$$
,
$$D$$
, and
$$B$$
on the circle.
$$\angle EAC \cong \angle DAB$$
.
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What is the relationship between
$$\overline{BD}$$
and
$$\overline {EC}$$
?
Problem 3
Given diameter
$$\overline{CB}$$
, chords
$$\overline{DB}$$
and
$$\overline{CD}$$
, and radii
$$\overline{AC}$$
,
$$\overline{AD}$$
, and
$$\overline{AB}$$
, find the measure of
$$\angle CDB$$
.
[IMG]


correct_option_index: 1