Lines tangent to a circle passing through a point P
Write the center C, the radius and P.  Then press  

C1 =    C2 =    r =
P1 =    P2 =

Tangency points (Q, R) and directions of CQ, CP, CR:
Q1 =    Q2 =
R1 =    R2 =
d1 = °   d = °   d2 = °
Directions of the lines tangent:
dir T1 = °   dir T2 = °

If you have to put a coefficient using some function symbol (for example 1/5, √2), put it in a numerical form (0.2, 1.414213562373095), for example using this (or this)
notes


examples