б)

1) S = 1/2 ah = 1/2 × 32 × 12 = 32 × 6 = 192 см²

2) S = 1/2 ah

a = 2S/h = (2×100)/5 = 200/5 = 40 дм

д)

1) S = 1/2 (a+b)h = 1/2 × (3+6) × 1 = 9/2 = 4,5 см

2) S = 1/2 (a+b)h

h = 2S/(a+b) = (2×10)/(2+3)=20/5 = 4 дм

е)

1) S = 1/2 (a+b)h = 1/2 × (5+9) × 2,5 = 1/2 × 14 × 2,5 = 7 × 2,5 = 17,5 м²

2) S = 1/2 (a+b)h = 1/2 (b-2+b)h = 1/2 (2b-2)h

2b-2 = 2S/h = (2×30)/3 = 20

2b = 20 + 2

2b = 22

b = 11 см

a = b - 2 = 11 - 2 = 9 см