Angles Outside of A Circle
\(\beta = \dfrac{\text{m}\overset {\huge\frown} {\text{AC}} - \text{m}\overset {\huge\frown} {\text{DF}} }{2}\)
\(\text{m}\angle \text{ABC} = \dfrac{\text{m}\angle \text{AOC} - \text{m}\angle \text{FOD}}{2}\)
\(\alpha = \dfrac{\text{m}\overset {\huge\frown} {\text{AC}} + \text{m}\overset {\huge\frown} {\text{DF}} }{2}\)
\(\text{m}\angle \text{DEF} = \dfrac{\text{m}\angle \text{AOC} + \text{m}\angle \text{FOD}}{2}\)
Segments From Secants
If two secants are drawn from a common point outside a circle then \(\:\color{blue} a(a + b) = c(c + d)\)
Exercise