Find the missing measure for a right circular cone given the following information find r if Total Area = 12 pi and Lateral area = 8pi

In the figure below, segment ac is congruent to segment ab: which statement is used to prove that angle abd is congruent to angle acd? a.)triangle acd is similar to triangle abd. b.)triangle acd is congruent to triangle abd. c.)segment a. d. is congruent to segment ac. d.)segment a. d. is congruent to segment dc.