Question

4. A line y=x makes of angle with positive side of X axis. ​

Answer 1

Answer:

makes with the positive X axis in the old coordinate system is arctan(−ab). The angle that the line ax+by+c=0 makes with the positive X axis in the new coordinate system is arctan(ba). The angle that this line makes with the positive Y axis in the old coordinate system is arctan(ba).