Geometry Circles, Tangents, and Arcs and Angles review for Test 6/5/2026

for study :)

A line is tangent to a circle if it is

perpendicular to a radius at the point of tangency

How to determine if a line is tangent to a circle?

Use Pythangorean theorem, equal is yes

Intersecting tangents are

Congruent

If polygon is circumscribed around a circle then,

all sides are tangent

Intersecting chords inside a circle

Part x Part = Part x Part

Intersecting secants outside a circle

Outside x Whole = Outside x Whole

Intersecting secant and tangent outside the circle

Tan2 = Outside x Whole

If you get 4x2 when finding multiple answers,

Find GCF, then solve

Circle

All points are equidistant from center (Circle P)

Radius

segment with endpoints in center and on circle

Chord

Segment with endpoints on circle

Diameter

Chord that passes through center

Secant

line that intersects circle in 2 places

Tangent

line that intersects circle in one place

Point of Tangency

The point where the Tangent intersects the circle

Central angle

angle with vertex at center, and two radii sides (<APB)

Radii

plural radius

Inscribed angle

angle with vertex on circle, and two chord sides (<ACB)

Arc

portion of edge of circle defined by two endpoints (Curved line symbol)

Minor Arc

arc with measure less than 180* (2 Letters with curve)

Major Arc

arc with measure greater than 180* (3 Letters with curve)

Semicircle

arc with endpoints on diameter (3 Letters with curve)

Circle Area formula

A=pie r2

Circle Circumfrence formula

C=2pie r or C=pie d

Circle Arc length formula

L=x(c) over 360, c- circumference, x-degree of arc

If an inscribed angle intercepts a diameter then it is a

right angle

If two inscribed angles intercept the same arc, than they are

congruent

If quadrilateral is inscribed in a circle, than its opposite angles are

Supplementary

The measure of inscribed angle is

Half the outside arc

The measure of Central angle is

equal to arc

To find angle created by two intersecting chords not at center

Each set of vertical angles is the average of corresponding arcs

When chord and tangent intersect on circle

the supplementary angles are half of the intercepted arc

For finding outside angle of intersecting secants, secant-tangent, and two tangents

subtract intercepted arcs, and divide by 2