如图,扇形OAB的半径OA=3,圆心角∠AOB=90°,点C是弧AB上异于A(国外英文资料).docVIP

如图,扇形OAB的半径OA=3,圆心角∠AOB=90°,点C是弧AB上异于A(国外英文资料) Comparison and analysis of brothers Lian examination in senior high school entrance examination Zhang Lingling, postcode, Chongren Town, Shengzhou City, Zhejiang province 312400 Cai Jianfeng, Department of teaching and research, Shengzhou City, Zhejiang province 312400 In 2000, Shanghais mid-term exam and the final examination of Guangzhou city in 2008 had the similarities between the geometry background and the examination knowledge. It belonged to the brothers even examination questions. The younger brother examination question has inherited the bright spot of brother test question, and has carried on the independent innovation under the new curriculum background, has effectively examined the student to use the already learned knowledge, the analysis question and solves the question comprehensive analysis ability. The following brothers questions are compared and analyzed as follows: In 1 cases, (2000 Shanghai City senior high school entrance examination questions) as shown in the radius of 6 AB, arc central angle of sector OAB 90o, there is a point of P, PH group OA, pedal H, Delta OPH Center for G. (1) when the point P moves on the arc AB, is there a line segment in the segment GO, GP, and GH that has no length? If so, point out the line segment and find the corresponding length; (2) set PH=x, GP=y, and ask y to parse the function of X, and write the domain of function; (3) if PGH is an isosceles triangle, calculate the length of the line PH. Solution (1) the line whose length remains unchanged is GH, and GU=2 Extend the HG / OP in C, G is the focus of delta OPH dreams, Hence CH is hypotenuse OP the median, R GH=CH=OP= (2) PG OH extended to D, PH=x * OH= dreams, DP= * y=GP= (0 x 6) (3): PGH in a classified discussion If GP=PH, a simplification, R: If GP=GH, a solution (not virtually eliminated) If PH=GH, there is [comment] (1) the question mainly captures the nature with the same radius, while the P movement in t