Răspuns:
Explicație pas cu pas:
1)
a)
6-9x+1 =20x-8
6+8+1 =20x+9x
15=29x
29x=15
x= 15/29
-
b)
= 7:( 25/10-²⁾2/5) +11/30 :5/3 -1
=7 : (25/10-4/10) + 11/30⁽³*3⁽³/5 -1
=7 : 21/10 +11/50-1
=7⁽⁷*10/21⁽⁷+11/50-1
=⁵⁰⁾10/3+³⁾11/50 -¹⁵⁰⁾1
=500/150+33/150-150
=683/150
-
15+45=150 ( 1/2 din noul rest )
150+45=195 ( a doua zi)
150*2=300 ( 2/3 din rest)
300:2=150 (prima zi )
150x3=450 (suma de la început )
-
Aplicam teorema lui Thales
EF║BC →AF/AC =AE/AB
AF/36=12/18
AF=36*12/18= 24cm
EB= AB-AE =18-12 =6 cm
FC=AC -AF =36-24=12cm
-
∡ADC=120
∡DAB= 60
∡ABC=60
∡DCB= 120
CM= inaltime
ΔCMB - ∡M=90
-∡ABC= 60
∡MCB= 180- (60+90)=30
↓
conform teoremei ∡ de 30 °
↓
MB= 7/2=3,5 cm
AB= 3,5+3,5+8= 15 cm
Aria trapez= (B+b) *h/2
Aria trapez=´[ (15+8) *10]/2=23*10/2=230/2= 115 cm ²
P trapezului =8+ 15+ 7+ 7 =37 cm
