Answer:
DC⊥EF as the 2 angles in smallest triangle are 30 and 60 degrees, so the last one is 90 making Line DC perpendicular to Line EF.
Explanation:
DC⊥EF means that Line DC is perpendicular (90 degrees) to EF.
To prove this, we can use the two angles of the small triangle created by the intersection of the triangles AEF and DCB.
The remaining angle of triangle AEF is 60, as all angles of triangles add up to 180 (so 180 - 12 = 60). This angle at F is shared with the little triangle.
Now we will get the angle at D using the triangle DCB. Since we are given two angles 90 and 60, angle D has to be 30.
So of our little triangle, we have angles 30 and 60, meaning the last one is 90 degrees and hence, DC⊥EF