ExplanationTo help with discussion, we have labeled points on the figure.
Start with triangle ACF. Angle A is 90° and angle C is 30°, so angle AFC must be 60° (180° – 90° – 30° = 60°).
If AFC is 60°, then EFD must be 120° (180° – 60° = 120°).
Now you can find angle FDE, which we have called angle z: (180° – 120° – 40° = 20°). If z = 20°, then x = 160°, because x + z = 180°.
Hence x x = 160°.Attachment:
di new.jpg [ 17.45 KiB | Viewed 100090 times ]
Attachment:
di new1.jpg [ 17.99 KiB | Viewed 100247 times ]
Attachment:
di new2.jpg [ 18.88 KiB | Viewed 100012 times ]
Attachment:
di new3.jpg [ 19.44 KiB | Viewed 100028 times ]