AB = 5 cm
AC = 8 cm
ugol A = 30°
S treug = 1/2* (AC)*h .... pust AC y nas - osnovanie treugolnika, i togda visota h = lejit naprotiv ygla A (extra-knowledge = h - eto katet pryamougolnogo treugolnika, c protivolejazhshim yglom A i gipotenyzoi AB..... a esli "protivolejazhshiy" - to etot katet avtomaticheski raven sinA * AB)
h = AB * 1/2...... Ny, tak vishlo, chto sinus 30° raven polovinke, proverte po kalkyliatory ili tablitsam Bradisa
I dalee:
S = 1/2 x AC x h = 1/2 x AC x 1/2 x AB..... podstavlyaem .... 1/2 x 1/2 X 5 x 8 = 40/4 = 10 sm^2