Three right-angled triangles are shown below. Each triangle is divided into an even number of sections of equal width, some of which are shaded.
a) For each triangle, find the ratio of the shaded area to the unshaded area.
Give each answer in its simplest form.
b) Using your answers to part a), suggest a general rule for this ratio when the triangle is split into 2n sections.
Your answer should be in its simplest form.