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回答 (1)
2017-07-18 2:25 am
✔ 最佳答案
Sum of interior angles of ΔRST :(x + 30)° + 3x° + 90° = 180°
4x = 60
x = 15
∠S = 3 × 15° = 45°
∠R = (15 + 30)° = 45°
Since ∠R = ∠S = 45°, then RT = ST = y
Area of ΔRST
= (1/2) × RT × ST
= (1/2) × y × y
= y²/2
收錄日期: 2021-04-18 17:16:39
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20170717182010AAOUOBE