第 42 題
△APR/△ABC = (AP * AR)/(AB * AC) = (2 * 1)/(3 * 5) = 2/15
△BPQ/△ABC = (BP * BQ)/(AB * BC) = (1 * 3)/(3 * 5) = 3/15
△CQR/△ABC = (CQ * CR)/(BC * CA) = (2 * 4)/(5 * 5) = 8/25
△PQR = (1 - 2/15 - 3/15 - 8/25)△ABC = (26/75)△ABC
第 44 題
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