Different frames are formed using a triangular structure as shown. Find the rule that will give the number of sticks in terms of the number of triangle frames. Also, find the number of sticks used in 9 triangle frames.
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Solution
Solution:
The first figure consists of 1 triangle made up of 3 sticks.
The second figure consists of 3 triangles made up of 7 sticks.
The third figure consists of 5 triangles made up of 11 sticks.
So, going by the pattern, the generalized rule is that the number of sticks is one more than twice the number of triangles.
Hence, the pattern is 2n + 1, where n is the number of triangles.
We have to find the number of sticks in 9 triangle frames that means n = 9.
So, number of sticks = 2 × 9 + 1
= 18 + 1
= 19 sticks.