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In geometry, the Parry point is a special point associated with a plane triangle. It is a triangle center and it is called X(111) in Clark Kimberling's Encyclopedia of Triangle Centers. The Parry point is named in honor of the English geometer Cyril Parry, who studied them in the early 1990s. ==Parry circle== Let ''ABC'' be a plane triangle. The circle through the centroid and the two isodynamic points of triangle ''ABC'' is called the Parry circle of triangle ''ABC''. The equation of the Parry circle in trilinear coordinates is : The center of the Parry circle is also a triangle center. It is the center designated as X(351) in Encyclopedia of Triangle Centers. The trilinear coordinates of the center of the Parry circle are : ''f''( ''a'', ''b'', ''c'' ) : ''f'' ( ''b'' , ''c'', ''a'' ) : ''f'' ( ''c'', ''a'', ''b'' ), where ''f'' ( ''a'' , ''b'', ''c'' ) = ''a'' ( ''b''2 − ''c''2 ) ( ''b''2 + ''c''2 − 2''a''2 ) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Parry point (triangle)」の詳細全文を読む スポンサード リンク
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