Question

putin ajutor va rogg​

Answer 1

Răspuns:

Explicație pas cu pas:

AD = 20 cm ; tgB = 4/3

tgB = CE/BE = 20/BE = 4/3 =>

BE = 20·3/4 = 15 cm =>

AB = AE + BE = 20 cm + 15 cm = 35 cm

ΔBCE = dreptunghic =>

BC² = CE²+BE² = 20²+15² = 400+225 = 625

BC = √625 = 25 cm

P trapez = AB + BC + CD + AD =

= 35 cm+ 25 cm+ 20 cm+ 20 cm = 100 cm

P trapez = 100 cm

sin ACB = ?

AB/sinACB = AC/sinB

sinB = CE/BC = 20/25 = 4/5

AC² = AD²+CD² = 20²+20² = 400+400 = 800

AC = √800 = 20√2 cm =>

sinACB = AB·sinB / AC = (35·4/5) /20√2 = 28/20√2 = 7/5√2 =

= 7√2/10