Hi,
Apologize, misread the question:
∠c = ∠1 - ∠2 0r ∠1 = ∠c + ∠2
To my knowledge, the idea would be to construct varius examples, that is,
different sizes for angle c and angle 2 and show how that effects the size
of that angle 1. Might recommend showing angle 1 at 90°(2 & c complementary angles)
and ∠1 at 180°(c & 2 suplementary angles forming a 'straight line')
One ex below where angle ∠1 < 90°