圓O的半徑位25,弦AB,CD相交于點P,AP=BP=20,CD=48,設角APC=α,則Sinα的值為多少?
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做OQ垂直于CD，Q為垂足。OQ^2 = r^2 - (CD/2)^2 , OQ = 7OP^2 = r^2 - AP^2 = 15, PQ^2 = OP^2 - OQ^2, PQ = 4*genhao11角APC = 角POQ === sinα = sin角POQ = PQ/OP = 4*genhao(11)/15
圓O的半徑位25,弦AB,CD相交于點P,AP=BP=20,CD=48,設角APC=α,則Sinα的值為多少?
做OQ垂直于CD，Q為垂足。OQ^2 = r^2 - (CD/2)^2 , OQ = 7OP^2 = r^2 - AP^2 = 15, PQ^2 = OP^2 - OQ^2, PQ = 4*genhao11角APC = 角POQ === sinα = sin角POQ = PQ/OP = 4*genhao(11)/15