A-B=(3x+2)²-(√3x-1)²
a-b=9x²+12x+4-3x²+2√3x-1=6x²+12x+2√3x+3
3) 8x-12+18x-12=12x-9-1
8x+18x-12x=-9-1+12+12
14x=14
x=14/14=1
x=1
5) AD=12 DC=16
in Δ adc dreptunghic cu d=90 grade cu TP
ac=√ad²+dc²
ac=√12²+16²
ac=√144+256
ac=√400
ac=20
in Δ ABC dreptunghic cu a=90 grade folosim functiile trigonometrice
cos C=AC/BC
cos 30=√3/2
√3/2=20/BC
BC=20*2/√3
BC=40/√3
BC=40√3/3
cu TP aflam pe AB
AB=√BC²-ac²
ab=√(40√3/3)²²-20²
ab=√4800/9-400
ab=√1200/9
ab=20√3/3
A=BC*AD/2
A=40√3/3*12/2
A=80√3
