jawab no 15 PAKE CARA YAH!

Keliling segitiga = sisi alas + tinggi + miring
40 cm = 8+x+5+x+7
40 cm = 20+2x
10 cm = x

Alas = 8 cm
Tinggi = x+5 = 15 cm
Miring = x+7 = 17 cm

Luas = 1/2 × a × t
= 1/2 × 8 × 15
= 60 cm2

mencari nilai (x)
k = jumlah sisi sisinya
40 = 8 + x + 5 + x + 7
40 = 2x + 20
2x = 40 - 20
2x = 20
x = 20/2
x = 10

panjang AC
= x + 5
= 10 + 5
= 15 cm

luas ΔABC
= 1/2 x alas x tinggi
= 1/2 x 8 x 15
= 4 x 15
= 60 cm²