I'm doing my homework and I need to find out how to find the circumference of a semicircle with a radius of 4

Radius by definition is the length of the line between the circumference and the center of the circle. It is exactly half of the circles diameter.

Since the radius is the measurement from the center or is half the diameter; dividing the circle itself into two would not make any difference to the value of the radius.

So:

If the radius of the circle is 4 cm the radius of the same circle divided into two parts (semi-circle) would also be 4 cm.

The radius of the circle can be found

If the area of the circle is given by using the formula:

Area of a circle= 2πr

OR

If the circumference is given by using the formula:

Circumference=πr

OR

If the diameter is given:

r= d/2

Since the radius is the measurement from the center or is half the diameter; dividing the circle itself into two would not make any difference to the value of the radius.

So:

If the radius of the circle is 4 cm the radius of the same circle divided into two parts (semi-circle) would also be 4 cm.

The radius of the circle can be found

If the area of the circle is given by using the formula:

Area of a circle= 2πr

^{2 }OR

If the circumference is given by using the formula:

Circumference=πr

OR

If the diameter is given:

r= d/2

The radius is half of the diameter.