The figure below shows a "Size 3" equilateral triangle divided into 9.
"Size 1" equilateral triangles. The figure has 6 upward facing and 3 downward facing
"Size 1" equilateral triangles, 3upward facing and no downward facing
"Size 3" triangles. It has a total of 13 equilateral triangles of all sizes. the following size 6 triangle is divided up in the same way.what is the sum of the number of upfacing size 2 triangles and the number of upward facing size 4 triangles?
Option
a) 27
b) 17
c) 18
d) 19

• Where is figure??????
• 10 years agoHelpfull: Yes(0) No(0)
• In a size 6 triangle there are,
  
  1+2+3+4+5=15 size 1 triangle facing upwards
  
  1+2+3=6 size 4 triangle facing downwards
  
  So, totally 15+6=21 triangles
  
  
• 9 years agoHelpfull: Yes(0) No(0)
• In the previous answer I wrongly mentioned as downwards instead of upwards...
  
  In a size 6 triangle there are,
  
  1+2+3+4+5=15 size 1 triangle facing upwards
  
  1+2+3=6 size 4 triangle facing upwards
  
  So, totally 15+6=21 triangles
• 9 years agoHelpfull: Yes(0) No(0)