o路人甲o
2020-3-9 03:28:15
let P be a point on AE such that MP is perpendicular to AE. let Q be the point of projection on M on ABED. the required angle is MPQ. since it's a prism, Q lies between DE
1. use a to find MP
2. use EDM (60 degree), DM, and right angled triangle MQD to find MQ and QD
3. EQ=ED-QD
4. use AED(45degree), EQ and right-angled triangle EQP to find QP
5. apply cosine formula on triangle MPQ to find angle MPQ
或者就這樣吧
2020-3-9 03:34:34
想知 點樣睇到 let Q be the projection of M on ABED 呢一樣野
幅圖有冇咩特性令你諗到要咁let
Ads
o路人甲o
2020-3-9 03:34:52
最正路既諗法係首先由其一塊面拉條perpendicular line落common line, 之後將呢條perpendicular line project落另一塊面到
浮雲(真毒)
2020-3-9 03:35:31
此回覆已被刪除
o路人甲o
2020-3-9 03:40:46
angle between two planes 既定義咪要係個兩塊面拉perpendicular lines去common line上一點既， 咁個兩條perpendicular lines就要係對方既projection黎
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