Loading [MathJax]/jax/output/SVG/jax.js
 
  Questions   
Sort: 
 #1
avatar+19 
0
Dec 11, 2018
 #1
avatar+258 
+1
Dec 11, 2018
 #2
avatar+505 
0
Dec 11, 2018
 #4
avatar+26396 
+10

7. 

As shown in the diagram, points B and D are on different sides of line AC. 

We know that Angle B=2*Angle D=60 degrees and that AC=4sqrt(3). 

What is the distance between the circumcenters of Triangle ABC and Triangle ADC?

 

line segments:

Let AC=43 Let AG=GC=23 Let AE=EC=r Let AF=FC=R Let FE=EG+GF 

The distance between the circumcenters of Triangle ABC and Triangle ADC =FE

 

angle:

Let ABC=60 Let ADC=ABC2=30 Let AEC=2ABC=120 Let AFC=2ADC=60 

 

EG= ?

AC2=2r2(1cos(120))cos-rule|cos(120)=0.5(43)2=2r2(1+0.5)48=2r2(1.5)24=r2(1.5)r2=16AG2+EG2=r2(23)2+EG2=1612+EG2=16EG2=4EG=2

 

GF= ?

AC2=2R2(1cos(60))cos-rule|cos(60)=0.5(43)2=2R2(10.5)48=2R2(0.5)24=R2(0.5)R2=48AG2+GF2=R2(23)2+GF2=4812+GF2=48GF2=36GF=6

 

FE=EG+GF=2+6FE=8

 

The distance between the circumcenters of Triangle ABC and Triangle ADC is 8

 

laugh

Dec 11, 2018
 #3
avatar+26396 
+12

George is about to get a certain amount of change less than one dollar from the cash register.

If he gets the most quarters possible and the rest in pennies, he would need to receive 3 pennies to meet the amount.

If he gets the most dimes possible and the rest in pennies, he would need to receive 8 pennies to meet the amount.

What is the sum, in cents, of the possible amounts of change that he is trying to get?

 

Let n= quartersLet m= dimes

 

Formula:

25n+3=10m+810m=25n5m=25n510=20n+5n510=20n10+5n510 | cut off whole partsm=2n+5n510=am=2n+a(1)a=5n51010a=5n55n=10a+5|:5n=2a+1(2)m=2n+a=2(2a+1)+am=5a+2(3)

 

conclusion:

n=2a+1aZm=5a+2aZ

 

solution:

aquartersdimespennies01228137782512128>$1 !

 

laugh

Dec 11, 2018

0 Online Users