# Thread: Convert semicircle to sq millimeters

1. ## Convert semicircle to sq millimeters

What is the mathematical formula to convert a circle to square millimeters.
Thanks

2. Originally Posted by Risrocks
What is the mathematical formula to convert a circle to square millimeters.
Thanks
Do you mean how do you find the area? The semicircle is half a circle so
$A = \frac{1}{2} \pi r^2$

-Dan

3. G'day Dan,

Thanks, but I'm being asked to "calculate the area of the semicircle in sq mm". I did A = \frac{1}{2} \pi r^2 = 1.57. I don't know the formula to convert the area of 1.57 to sq mm. Hope this makes sense, and thanks for your help.

4. Depends on what we're converting from. Is your radius in centimetres, metres, millimetres, inches, ... ?

5. Please see attachment, which displays diagram for question "calculate the area of semicircle in sq mm". Thanks again.

6. Well then no conversion needs to be done since your radius is already in mm. Just simply find the area.

This may help: if you had a square with dimensions 5 metres by 5 metres, then the area would be 25 metres squared or square metres (The term 'square' refers to the fact that you're dealing with a concept in 2 dimensions). You wouldn't say the area is 25 metres.

7. Thanks very much. As you can see, Complex Maths is not my forte but I need to complete as part of my Residential Drafting Certificate.

8. Originally Posted by Risrocks
G'day Dan,

Thanks, but I'm being asked to "calculate the area of the semicircle in sq mm". I did A = \frac{1}{2} \pi r^2 = 1.57. I don't know the formula to convert the area of 1.57 to sq mm. Hope this makes sense, and thanks for your help.
$A=\frac{1}{2}\pi r^2$
$A=\frac{1}{2}\pi (50)^2$
$A=1250 \pi mm^2 \approx3926.99 mm^2$