Lines and Angles

Question

In figure, if AB || CD, EF ⊥ CD and ∠GED = 126°, find ∠AGE, ∠GEF and ∠FGE.


Answer

(i) ∠AGE = ∠GED = 126°
| Alternate Interior Angles
(ii)    ∠GED = 126°
⇒ ∠GEF + ∠FED = 126°
⇒ ∠GEF + 90° = 126°
| ∵ EF ⊥ CD ∴ ∠FED = 90°
⇒    ∠GEF = 126° - 90° = 36°
(iii) ∠GEC    + ∠GEF + ∠FED = 180°
| ∵ CD is a line
⇒ ∠GEC + 36° + 90° = 180°
⇒    ∠GEC + 126°= 180°
⇒    ∠GEC = 180° - 126° = 54°
Now,    ∠FGE = ∠GEC = 54°
| Alternate Interior Angles

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