Hello,
1) draw [AB]
2) draw mes (BAB')=78° (|AB|=|AB'| (distance))
draw the circle center B' passant by A.
3)C=middle [BB']
4) draw the half circle with [BB'] as diameter.
5) Intesection of cercle =>D
explain: any right triangle is inscribed in a semicircle
Rem: 78+90=168 and 360-168=192