What is the basis of Complimentary Angles.
It is based on naming of t-ratios as Complimentary in pairs.
How are Similar Triangles and Congruent Triangles related.
If areas of two Similar triangles equal, then triangles are Congruent also
How to proceed in learning 3-D Geometry.
Proceed explaining Lines in 3-D starting from Straight Lines in 2-D and modify to 3-D.