圖中,XY為一平面鏡,A和B是鏡前的兩點,它們相距12cm,兩點分別距離平面鏡8cm和5cm,
現將一電筒放在點A,使光線由點A射出,在平面鏡上的點E反射後穿過點B.若EF平行XY,且角AEF=角BEF,求光線的入射角的角AEF.
maths 10分 幫我計!
2007-12-13 3:11 am
回答 (1)
2007-12-14 4:56 am
✔ 最佳答案
Let Angle AEF = QDistance of AE along XY Plane = 8tanQ
Since Angle BEF = AEF =Q
Distance of BE along XY Plane = 5tanQ
Distance between AB along XY Plane = 8tanQ + 5tanQ = 13tanQ
Offset Distance of A and B from mirror = 8 - 5 = 3cm
Distance between AB parallel to mirror = (12^2 - 3^2)^0.5cm = 11.619cm
Equating : 13tanQ = 11.619
tanQ = 0.894
Q= 41.78 degrees
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