Brian and shadow to Z point math hypotenuse of a right triangle .
Tree and shadow to the right-angled triangle hypotenuse well .
Shadow length depends on the angle of incidence of solar prmieni . The angle of Padania , in both cases the same joke . So tangents hypotenuse same joke .
tg = a/b
Brian
a/b = 6ft/4ft = 1,5
A tree
a/b = a/20ft
a/20ff = 3/2 We multiply the cross
2a = 60ft
a = 30tf
Answer : The tree is 30 feet
