How do you find the area and circumference of a half circle?

Multiply the radius by 2 to get the diameter, then multiply it by pi (3.14) to get the circumference, then divide by two, since its a half circle

The perimeter of a circle is π × d where d is the diameter so half of that is 1/2 π × d. But If you are going to walk around a semicircle you need to go half way around thecircle and then across a diagonal to get back to where you started so the perimeteris 1/2 π × d + d.