The diagrams present a run of triangles constructed from identical sticks. Compared with the triangle before it, each one has two extra sticks on every edge.
(a)[1]
Complete the column for triangle $4$
(b)[1]
Find an expression in terms of $n$ for $x$.
(c)[1]
Find an expression in terms of $n$ for $y$.
(d(i))[1]
Write down the total number of sticks in the first four triangles
(d(ii))[2]
Find an expression in terms of $n$ for the total number of sticks in the first $n$ triangles.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “$7,\;21$” …