Через Th пифагора найдем сторону ab:

ac^2 = ab^2 + bc^2

=> ab^2 = ac^2 - bc^2

=> ab = sqrt(ac^2 - bc^2) = 10

sin A = bc / ac = 24/26 = 12/13

cos A = ab / ac =  10/26 = 5/13

tg A = bc / ab = 24/10 = 12/5

ctg A = ab / bc = 10 / 24 = 5/12