Question

Dererminati aria patrulaterilui......

Answer 1

Răspuns:

ΔMAD este dreptunghic in ∠ MAD  si m(∠ ADM)= 30° => AM = $\frac{MD}{2}$

AM^2 + AD^2 = MD^2

<=> AM^2 + AD^2 = (2AM)^2 = 4 AM^ 2  | - AM^2

<=> AD^2 = 3 AM^2 => 3 AM^ 2 = 12| : 3

=> AM^2 = 4 => AM= 2 cm

=> $\frac{2}{BM}= \frac{4}{3}$ => BM = 2*3/4 = 1,5

=> AB = 2+ 1,5 = 3,5 cm

=> A ΔADCB = 3,5* 12 = 42 $cm^{2}$

A Δ AMD = AD* AM /2 = 12* 2 /2 =12 $cm^{2}$

A MDCB = A ADCB - A Δ ADM = 42 $cm^{2}$ - 12 $cm^{2}$  = 30 $cm^{2}$

Answer 2

Răspuns:

Explicație pas cu pas:

In Δ AMD   ∡ADM =30°     ⇒AM=AD/2=12/2=6 cm

AM/MB=4/3=AM/AB=4/7     AB=6×7/410,5 cm

Abmdc=Aabcd-Aamd

Aamd=AM×AD/2=6×12/2=36 cm²

Aabcd=10,5×12=126 cm²

Abmdc=126-36=90 cm²