Answer:
circumference is 50.24cm
Step-by-step explanation:
π
= 200.96
r = 
= 
=8
Circumference = 2πr = 2 x.3.14.x 8 = 50.24
To find percent error it's the absolute value of
Actual-Experimental divided by The actual times 100
1) 6-5.43
2) 0.57/6
3) 0.095x100
4)9.5%
1) 110+30+a = 180
a = 180-140 = 40
Obtuse angled triangle
2) 50+50+C = 180
C=180-100 =80
Acute angled triangle
3) 45+45+b =180
b =180-90 = 90
Right angled triangle
4) 45+60+C = 180
C = 180-105 =75
Acute angled triangle
5) 94+47+b =180
b = 180-141=39
Obtuse angled triangle
6)81+53+a = 180
a =180-134 = 46
Acute angled triangle
7) 38+45+b =180
b = 180-83 =97
Obtuse angled triangle
8) 36+54+C =180
C =180-90 = 90
Right angled triangle.
The equation of a circle with center 
and radius 
is
In your case,
Plug these values into the generic formula and you'll get your equation.
It is 12 because there are 180 degrees in a set of supplementary angles and 12 times 10 equals 120, plus 60 equals 180.
