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 (1/5,π,√2,...), put it in a numerical form (calcolatrice)
notes

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