Number Patterns in Geometric Figures

The following is a sequence of patterns consisting of triangles and circles joined by straight lines.

The first three patterns are shown below:

1. How many circles are there in the \({4}^{\mathrm{th}}\) pattern?
2. How many straight lines are there in the \({5}^{\mathrm{th}}\) pattern?
3. Write down, in terms of \({n}\),
   1. the number of circles,
   2. the number of lines,
   3. the difference between the number of circles and triangles, in the \({n}^{\mathrm{th}}\) pattern.