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Arc(CB)  =  90^o.

Arc(CBH)  =  90^o + 57^o  = 147^o.

 

Perimeter of circle  =  2·pi·r  =  2·pi·60  =  120·pi cm.

 

Portion of the circle:  arc(CBH)  =  147^o / 360^o.

 

Length of the arc =  (147/360)·120·pi cm

 

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