Draw a surface by connecting A,B, and C. Draw you’re cone by connecting E,F, and G

Intersecting the previous cone and surface will give you line A

E C

A

B

G

F

Intersecting the cone and the suface will give you line A

A

E

C

A

B

G

F

Connect A,B,C and make a surface. Use line G and point E and F to make a cone.

A

Network srf. the lines to get the minimal surface