It shows a circle cut in half and on the line that cuts it in half it says 14 CM. Then it says PI = 3 1/7. It then asks to find the perimeter of the circle. Can someone help. It has been a while since I did this stuff. She says the answer is around 36....not sure.
Thanks
2007-05-13 14:07:04 · 6 answers · asked by flafuncop 2 in Science & Mathematics ➔ Mathematics
Perimeter of circle = 2xpixr, r = radius
Radius = diameter/2... In this case the line 14cm is the diameter, hence, radius is 14/2 = 7
So perimeter of the circle = 2xpicr = 2xpix7, but pi = 22/7
So perimeter of circle = 44cm
However, you only have half circle so perimeter is half circle + line = 22cm + 14cm = 36cm
2007-05-13 14:13:16 · answer #1 · answered by looikk 4 · 2⤊ 0⤋
So the circle has been cut in half - the line that bisected it is the diameter, and it's 14cm. Pi is the math constant and has a value of (22/7 or 3&1/7) or 3.142...
For circles, perimeter is called circumference, and it is given by pi(d) or 2*pi*r, where d = diameter, and r=radius.
So in your case, the answer is:
C = pi*d= (3 1/7)*14 = 44cm
NOTE: I understand the question to be asking for the perimeter of the circle. This is not the perimeter of the semi-circle, or the circle + the diamater. There is only 1 formula for circumference and only 1 answer. Make sure you know what the question wants.
2007-05-13 21:16:30 · answer #2 · answered by Anonymous · 0⤊ 1⤋
You have a semi-circle whose diameter is 14 centimeters. The perimeter of the semi-circle is going to be the 14 cm line, PLUS the arc. The arc is just half of the circumference if the whole circle. The circumerfence of a circle is 2*pi*r where r is the radius, or simply pi * diameter. So the arc part of this is half of this, or (pi*14)/2.
They want you to use 3 1/7 as the (bad) approximation of Pi. So the answer is 14 + (3 1/7)(14)/2. Just calculate this out.
2007-05-13 21:15:43 · answer #3 · answered by Anonymous · 3⤊ 0⤋
the periemeter of a circle is P=2(Pi)r or P=Pi * diameter so a circle with diameter of 14 has a periemeter of ~44
(3.14159) * 14 = 43.982
or Using (3 1/7) * 14 = 44
Since you are only using Half of the circle Divide by 2
44/2 = 22
now add the center (interior diameter) line 14 to arrive at your answer 36
22+14 = 36
2007-05-13 21:18:03 · answer #4 · answered by agill15806 2 · 1⤊ 1⤋
Diameter = 14cm
Circumference = pi.d
=22/7 * 14 cm
=44cm
Perimeter of semicircle = (1/2)* circumference diameter
=1/2 * 44cm + 14cm
=22cm + 14cm
=36cm
2007-05-13 21:22:13 · answer #5 · answered by gudspeling 7 · 1⤊ 0⤋
the line that cuts it in half is the diameter. the equation of the perimeter is pi times the diamter, so 14pi or about 44
2007-05-13 21:10:20 · answer #6 · answered by dpmwcml 2 · 0⤊ 1⤋