Page 13 - Trigonometry

Example 4:

A pattern is made from a disc of diameter F residing
on a rectangle of length A and width E. Derive an

expression for the length of the perimeter of the

pattern.

Mark out the chord on the
circle. The radius of the circle

is F/2 and the chord length x is

given by,

= sin ( ) 1
2

The arc length is given by where θ is measured in
2
radians. From the small triangle,

/2
cos ( ) = = 2
2 /2

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