The figure shows a pattern formed using some sticks.
- How many sticks are needed to form 8 triangles?
- How many triangles are formed using 85 sticks?
1 triangle = 1 + (2 x 1) = 3 sticks
2 triangles = 1 + (2 x 2) = 5 sticks
3 triangles = 1 + (2 x 3) = 7 sticks
Formula Number of sticks = 1 + (2 x Number of triangles)
(a)
8 triangles
= 1 + 2 x 8
= 17 sticks
(b)
1 + (2 x Number of triangles) = 85 sticks
2 x Number of triangles = 85 - 1 = 84 sticks
Number of triangles = 84 ÷ 2 = 42
Answer(s): (a) 17; (b) 42
