Question

A student solved the following problem and made an error:


I've tried line 2 and line 3 already and they were wrong.

Answer 1

these are the triangles

Answer 2

lines 1 through 3: http://prntscr.com/8gmwzs

Answer 3

lines 4 through 6: http://prntscr.com/8gmx4v

Answer 4

In which line did the student make the FIRST mistake?
Line 3
Line 5
Line 1
Line 2