Try this solution:
1. if 't'⊥'a' and 't'⊥'b', then m(1)=90°;
2. if m(1)=90, then m(2)=90-22=68°;
3. if m(3)=180-m(2), then m(3)=180-68=112°;
4. if m(3)=m(4), then m(4)=112°;
5. if m(2)=m(5), then m(5)=68°;
6. if line '5-6'='5-7', then m(6)=(180-m(5))/2=0.5*(180-68)=56°;
7. if m(6)=56, then m(7)=180-m(6)=180-56=124°;
8. if m(7)=m(8), then m(8)=124°.
