A ________ B ABCD paralelogram
/ \ / AC_I_AD(sa zicem)
/ \ / D=60°
/ \ / AD=6cm
D /_______\/ C _____________________
[tex]P_{ABCD}=?[/tex]
In ΔADC dr :
A=90° |
| ⇒ C=30°
D=60° |
Aplicam cos de 60° :
cos D = [tex] \frac{AD}{DC} [/tex]
cos60°=[tex] \frac{6}{DC} [/tex]
[tex] \frac{1}{2} = \frac{6}{DC} [/tex] ⇒ DC=2·6=12cm
P_{ABCD}=2·6+2·12=12+24=36cm²
