Diketahui l = 40 cm, t= 10 cm dit = a ? cara mengerjakanya?

1/2 x alas x tinggi = luas segitiga
1/2 x alas x 10 = 40
5 x alas = 40
alas = 40 / 5 = 8 cm

L= 1/2.a.t
40 = 1/2 a. 10
40 = 5a
8= a