Question

Given: B, C, D, and E lie in plane m; 11 years ago

Answer 1

This theorem may help:
"If a line is perpendicular to each of two intersecting lines at their point of intersection, then the line is perpendicular to the plane determined by them."

Answer 2

Would that only prove that the angle ACD is perpendicular to the plane? Thank you so much for your help btw