Question

A yard with a tree is to be concreted. The owner wants to concrete the whole yard, but keep the tree in place and so concretes around the tree to its circumference. The tree has a circular cross section, with a diameter of 1 m. The yard is a rectangle, with sides of length 3 m and 4 m. What is the area of concrete required (to 1 d.p.)?

Answer 1

11.2 square meters

Explanation:

This is a very simple question. Basically, it's the area of a rectangle with the area of a circle subtracted. The area of a circle is calculated with the following formula:

`\pi * r^(2)`

Where r is the radius. We know the diameter is 1m, so we can simply halve this value to find the radius of 0.5m. Substituting in this value, we find the area of the circle to be:

`\pi * {0.5}^(2) \approx0.78539816339744830961566`

Now let's calculate the area of the rectangle, which is simply 3x4=12. Subtracting our earlier value from 12, we are left with an answer of 11.2 (to 1 d.p)