In the figure, BC is a straight line. ∠ADB = 90°, ∠EDF is equal to ∠FDC but 27° more than ∠ADE.
- What line is perpendicular to BC?
- Find ∠EDF.
(a)
Line AD or DA is perpendicular to BC
(b)
∠EDF = ∠FDC = 1 u
∠ADE = 1 u - 27°
1 u + 1 u + 1 u - 27° = 90° (Right angle)
3 u = 90° + 27° = 117°
1 u = 117° ÷ 3 = 39°
Answer(s): (a) AD or DA; (b) 39°