Question

Fie ABCD un dreptunghi:
Daca aria ABCD = 98cm, AB=2BC, calculati AB si BC;
Daca aria abcd = 192,5cm, AB=2,5cm, calculati BC;
Daca AB= 3/7 •BC si aria abcd = 84 cm, calculqti ab si ac

Answer 1

1)notam BC =x
AB =2x
A =L *l
98 =2x *x
98 =2x ^2
x ^2 =98/2
x ^2 =49
x =7  ;BC =7cm
AB =2*7
AB =14 cm
2)A =192.5cm
A =L* l
192.5 =2.5 *l
l =192.5 /2.5
l =77  ; BC =77 cm
3)A =84cm  ;AB =3*BC /7  (notam BC =x)
A =L * l
84 =3x /7 *x
84 =3x ^2 /7
3x^2 =84 *7
3x^2=588
x^2 =588/3 =196
x =14  ;BC =14 cm
AB =3BC /7 
AB =3*14 /7
AB =6cm