Question 588140
A chord of a circle is 10mm.
 It is parallel to a tangent and bisects the radius drawn to the point of tangency(where the line and the circle touch).
 Find the circumference of the circle.
:
Draw this out and you can see two right triangles are formed where
side 1 = 5 (half the chord)
side 2 = .5r (half the radius
hypot: = r
:
r^2 = (.5r)^2 + 5^2
r^2 = .25r^2 = 25
r^2 - .25r^2 = 25
.75r^2 = 25
r^2 = {{{25/.75}}}
r^2 = 33.33
r = {{{sqrt(33.33)}}}
r ~ 5.7735 is the radius
Find the circumference
c = {{{2*pi*5.7735}}}
c = 36.276 is the circumference