a) 3(5x-2)+5x-4(2x-1)=12(3-2x)-18
15x-6+5x-8x+4=36-24x-18
12x-2=18-24x
36x=20
x=20/36=5/9
2a) sin30xcos60+sin60xcos30=sin(30+60)=sin90=1
b)cos60xcos30-sin60sin30=cos(60+30)=cos 90=0
c)sin60-2sin30cos30 =sin60-sin(30+30)=sin60-sin60=0
5 CE_I_AB
sin 30⁰=6/CB
1/2=6/CB
CB=12 cm
EB=√(12²-6²)=√(144-36)=√108=6√3
AB=2+6√3
P=2+√3+12+2+6=22+√3
AC=√(6²+2²)=√(36+4)=√40=2√10
DB=√[6²+(2+6√3)²]=√(36+4+24√3+108)=√(148+24√3)=4(√37+6√3) ????
7) DE_I_AB CF_I_AB
Δ ADE=ΔCBF dreptunghice si isoscele
AE=FE=DE=CF=10
DC=40-10-10=20
AF=EB=40-10=30
AC=DB=√(10²+30²)=√(100+900)=√1000=10√10
