Question

va rog mult,e urgentttt

Answer 1

4) a+b=26      a=26-b
5a+20b=370
5(26-b)+20b=370
130-5b+20b=370
15b=370-130
b=240:15
b=16 bancnote de 20
a=26-16=10 banc. de 5

5) cos60=AD/AB
1/2=AD/8
AD=8/2=4 cm
AB^2=AD*AC
8^2=4*AC
AC=64/4
AC=16 cm
DC=AC-AD=16-4=12
BD^2=4*12=48
BD=rad48=4rad3
Aria=16*4rad3/2=32rad3

Answer 2

4. Notam astfel
x-numarul total de bancnote de 5 lei
y-numarul total de bancnote de 20 lei
Obtinem ca
x+y=26
5x+20y=370
5(26-y)+20y=370
130-5y+20y=370
130+15y=370
15y=240
y=16(bancnote de 20 de lei);
x=10(bancnote de 5 lei);
5.a.  A ΔABC=sin<60·AB·AC
A ΔABC=√3/2·8cm·12cm
A ΔABC=48√3cm² ;
b. Avem ΔBAD-Δdreptunghic m(<D)=90 de grade.
Cateta care se opune unghiului de 60 de grade este egala cu jumatate din lungimea ipotenuzei ,deci
AD=AB/2=8/2=4cm
A-D-C-coliniare unde AD+DC=AC=12cm ⇒DC=8cm .