f.2數(三角學)

1)
The question should be " Prove AC//ED "
AC cannot be parallel to AD if A, C and D are not on the same line.
Angle BDC + Angle ABD = 180° ( int. angles, AB//CD )
Angle BDC + 121° = 180°
Angle BDC = 59°

Angle ACD + Angle CDE
= Angle ACD + Angle BDC + Angle BDE
= 47° + 59° + 74°
= 180°
So, AC//ED ( int. angles supp. )
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2)
Extend CD so CD meets BE at F
Angle BED + Angle DFE = Angle CDE ( ext. angle of triangle )
29° + Angle DFE = 124°
Angle DFE = 95°
Angle DFE = Angle ABE = 95°
AB//CF ( corr. angles equal )
As CD and CF lie on the same line,
AB//CD.

左邊個題proveAC//AD!?
好似冇咩可能....AD都唔係線