Explain the formula in the text for angle measure in the Cartesian model.

EXERCISES 11.1
1. Explain the formula in the text for angle measure in the Cartesian model.

2. Find the perpendicular line from (2, 3) to t = {(x, A 1 2x + 3v = 5).

3. Find a coordinate function for f = {(x, A I 2x + 3y = 51.
11.2 THE POINCARE DISK MODEL FOR HYPERBOLIC GEOMETRY