Theorems for Circle

Two Secants (When Secant Vertex is Outside)

AX • XC = BX • XD, where AX is the entire segment and XC is a sliver of it.

Secant-tangent theorem

Involves the relationship AX • XC = (BX)^2 where AX and XC are segments of a secant and BX is a tangent.

Two secants condition

Involves the equation a(a+b) = c(c+d) representing segments related to two secants outside a vertex.

Tangent-Tangent Theorem (Outside Vertex)

The relationship a^2 = b^2 applies, where a and b are segments created by the tangents.

Length of arc formula

Calculated using M/360(2piR) where M is the angle and R is the radius.

Two Chords

AB • CD (AB is a chord, CD is another chord).

Angle in a Semi-Circle Theorem

An angle inscribed in a semicircle is a right angle.

Inscribed Angle Theorem

Inscribed angles that subtend the same arc are equal.