Example
Ex 1:
Refer to the figure and evaluate x°.
Sol:
Angle at a point = 360°
 AOC + COD
+ DOE + EOF + FOB +
AOB |
= | 360° |
| 60° + 50° + 40° + 2x + 3x + 100° | = | 360° |
| 250° + 5x | = | 360° |
| 5x | = | 110° |
| x | = |  |
| x | = | 22° |
Ex 2:
If AOB is a straight line then AOE is
equal to ?
Sol:
| AOC + COD + BOD |
= | 180° (Sum of 3 angles form a straight angle) |
| x + 18 + 50 + x + 24 | = | 180° |
| 2 x + 92 | = | 180° |
| 2 x | = | 180 – 92 |
| 2 x | = | 88° |
| x | = | 44° |
| BOE |
= | 3 x |
| = | 3 x 44 | |
| = | 132° | |
| AOE + BOE |
= | 180° [The angles form a linear pair] |
| 132° + AOE |
= | 180° |
| AOE |
= | 180 – 132° |
| = | 48° |