Question

If the diameter of the semicircle is 1.7 centimeters, what is the circumference of the semicircle?

Answer 1

The formula for circumference is $C=2 \pi r$ or $C= \pi d$.  We have a diameter for the semicircle, so let's use the diameter formula.  $C= \pi (1.7)$ which is either $C=1.7 \pi$ or C = 5.338 if we multiply pi in as 3.14.  BUT this is only half a circle, so we only have half that distance around the outside.  Therefore, the circumference of half this circle is 2.669 cm.  But we need to add the 24 mm in.  24 mm in centimeters is 2.4 cm.  So 2.669 + 2.4 = 5.069