How to calculate surface area of odd-shape?

PrecisionEdge

Hey Guys, I'm struggling to measure this odd shaped garden i have to Mulch at 100mm thick. 

I've broken it down to 4 shapes to make it easier but i'm second guessing myself on my maths. 

Left Hand Triangle = 3.1m2

Right Hand Triangle = 3.4m2

Rectangle = 10.5m2

Semi Circle = 20m2

Total Surface Area = 37m2 

At 100mm Thick should equal = 3.70m3

Does this look Correct

Appreciate Any Help.

Cheers.

EricL

Hello @PrecisionEdge 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question regarding the calculation of the surface of an area.

Your breakdown of the garden area and the calculations for the mulch required appear to be accurate. You've divided the area into four shapes: two triangles, a rectangle, and a semi-circle. The left triangle has an area of 3.1 m², while the right triangle covers 3.4 m². 

The rectangle's area is 10.5 m², which is calculated by multiplying its length and width. For the semi-circle, using the radius derived from the given diameter, the area comes to approximately 20 m². 

When you sum all these areas, the total surface area is 37 m². To mulch this area at a thickness of 100 mm (or 0.1 m), the volume required is calculated by multiplying the area by the thickness, resulting in 3.7 m³ of mulch. Everything checks out, and your calculations are correct.

If you need further assistance, please let us know.

Eric