Question

If a ray CD stands on a line AB then prove that Angle ACD =Angle BCD = 180 degree

Answer 1

The higest angle that you could measure is 360° that you can find if you just take end point of ray or a line segment, but as you take any point except end point on a line, ray or a line segment, then it may have 180° . As in the question the ray is cutting this angle of 180° so the sum of angle ACD and BCD must be equal to 180°.