Odpowiedź:
zad 15
l)
P - pole trapezu = 20 [j]
b = 5 [j]
h = 3 1/3 [j]
[j] - znaczy właściwa jednostka
P = (a + b) * h/2
2P = (a + b) * h
2P = ah + bh
ah = 2P - bh
a = (2P - bh)/h = (2 * 20 - 5 * 3 1/3) : 3 1/3 = (40 - 5 * 10/3) : 10/3 = (40 - 50/3) * 3/10 =
= (40 - 16 2/3) * 3/10 = (39 3/3 - 16 2/3) * 3/10 = 23 1/3 * 3/10 = 70/3 * 3/10 =
= 70 * 1/10 = 70/10 = 7
zad 16
b)
P - pole = 8,2 * 4,5 = 5,3 * h
8,2 * 4,5 = 5,3 * h
36,9 = 5,3 * h
h = 36,9 : 5,3 = 6 51/53
c)
P - pole = (12 * 15)/2 = (18 *h)/2
(12 *15)/2 = 18h/2
180/2 = 18h/2
90 = 18h/2
2 * 90 = 18h
180 = 18h
h = 180 : 18 = 10