Suppose that r is parallel to s and t is parallel to v. If the measure of angle 1=111 degrees?

Question

find the measure of angle 12.

.......R.l............l.S.......

..........l............l...........

..........l............l.........

T____1l2_____3l4____

.........5l6........7l8........

...........l...........l..........

V____9l10__11l12____

........13l14...15l16.......

...........l...........l............

...........l...........l...........

Answer 1

Since R // S

∠(1) = ∠(3) = 111ْ    

Since T // V

∠(3) = ∠(11) = 111ْ    

∠(12) = 180 - 111 =69ْ

Answer 2

69. If angle 1 is 111, then angle 6 is also 111. Also, this means angle 11 is 111, so subtract 111 from 180 to get angle 12, which is 69.