Answer:
use area to solve it
Step-by-step explanation:
When you mean estimate do you mean by rounding the first numbers?
Answer:
1 = 39 degrees (some theorem, like triangles sharing a bisector or something sorry)
3 = 51 degrees (if 1=39 and 2=90 degrees since its on a right angle, and a triangle's angles add up to 180, then you subtract 1 and 2 from 180 and get 51
Answer: 1) You forgot to change the sign over there. You have to subtract over there.
2) Just be careful while solving equations while changing the signs