Looking at the first figure
point A is labeled where two straingt lines are meeting below
point C is labeled at the centre of a hemisphere above
point B is labeled on the longest line of the two lines joining to form point A
looking at the second structure
two lines are meeting above to form a triangle having the same structure as the first figure. Therefore, point A will be labele at the top of two lines forming triangle
Point C will be label below which is the centre of the hemisphere shape.
looking at the frist figure the hemisphere shape like is above while for the second figure it is below
point B will be label on the longest side